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  • 1.
    Aguilar, Ximena
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Weise, Christoph
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sparrman, Tobias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wittung-Stafshede, Pernilla
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Macromolecular crowding extended to a heptameric system: the co-chaperonin protein 102011In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 50, no 14, p. 3034-3044Article in journal (Refereed)
    Abstract [en]

    Experiments on monomeric proteins have shown that macromolecular crowding can stabilize toward heat perturbation and also modulate native-state structure. To assess the effects of macromolecular crowding on unfolding of an oligomeric protein, we here tested the effects of the synthetic crowding agent Ficoll 70 on human cpn10 (GroES in E. coli), a heptameric protein consisting of seven identical β-barrel subunits assembling into a ring. Using far-UV circular dichroism (CD), tyrosine fluorescence, nuclear magnetic resonance (NMR), and cross-linking experiments, we investigated thermal and chemical stability, as well as the heptamer-monomer dissociation constant, without and with crowding agent. We find that crowding shifts the heptamer-monomer equilibrium constant in the direction of the heptamer. The cpn10 heptamer is both thermally and thermodynamically stabilized in 300 mg/mL Ficoll 70 as compared to regular buffer conditions. Kinetic unfolding experiments show that the increased stability in crowded conditions, in part, is explained by slower unfolding rates. A thermodynamic cycle reveals that in presence of 300 mg/mL Ficoll the thermodynamic stability of each cpn10 monomer increases by over 30%, whereas the interfaces are stabilized by less than 10%. We also introduce a new approach to analyze the spectroscopic data that makes use of multiple wavelengths: this provides robust error estimates of thermodynamic parameters.

  • 2.
    Bosco, Daryl A
    et al.
    Department of Biochemistry and Howard Hughes Medical Institute, Brandeis University, Waltham, MA, USA.
    Eisenmesser, Elan Zohar
    Department of Biochemistry and Howard Hughes Medical Institute, Brandeis University, Waltham, MA, USA.
    Clarkson, Michael W
    Department of Biochemistry and Howard Hughes Medical Institute, Brandeis University, Waltham, MA, USA.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Labeikovsky, Wladimir
    Department of Biochemistry and Howard Hughes Medical Institute, Brandeis University, Waltham, MA, USA.
    Millet, Oscar
    Protein Engineering Network Center of Excellence and Departments of Medical Genetics, Biochemistry, Canada.
    Kern, Dorothee
    Department of Biochemistry and Howard Hughes Medical Institute, Brandeis University, Waltham, MA, USA.
    Dissecting the microscopic steps of the cyclophilin a enzymatic cycle on the biological substrate HIV-capsid by NMR2010In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 403, no 5, p. 723-38Article in journal (Refereed)
    Abstract [en]

    Peptidyl-prolyl isomerases (PPIases) are emerging as key regulators of many diverse biological processes. Elucidating the role of PPIase activity in vivo has been challenging because mutagenesis of active site residues not only reduces the catalytic activity of these enzymes, but also dramatically affects substrate binding. Employing the cyclophilin A (CypA) PPIase together with its biologically relevant and natively folded substrate, the N-terminal domain of the HIV-1 capsid (CA(N)) protein, we demonstrate here how to dissect residue specific contributions to PPIase catalysis versus substrate binding utilizing NMR spectroscopy. Surprisingly, a number of CypA active-site mutants previously assumed to be strongly diminished in activity toward biological substrates based on a peptide assay only, catalyze the HIV capsid with wild-type activity, but with a change in the rate-limiting step of the enzymatic cycle. The results illustrate that a quantitative analysis of catalysis using the biological substrates is critical when interpreting the effects of PPIase mutations in biological assays.

  • 3.
    Bäckström, Stefan
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Centre for Molecular Pathogenesis (UCMP) (Faculty of Science and Technology).
    Huang, Shenghua
    Umeå University, Faculty of Science and Technology, Umeå Centre for Molecular Pathogenesis (UCMP) (Faculty of Science and Technology).
    Wolf-Watz, Magnus
    Chemistry.
    Xie, X Q
    Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Härd, Torleif
    Grundström, Thomas
    Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Sauer, Uwe
    Umeå University, Faculty of Science and Technology, Umeå Centre for Molecular Pathogenesis (UCMP) (Faculty of Science and Technology).
    Crystallization and preliminary studies of the DNA-binding runt domain of AML1.2001In: Acta Crystallogr D Biol Crystallogr, ISSN 0907-4449, Vol. 57, no Pt 2, p. 269-71Article in journal (Refereed)
    Abstract [en]

    The acute myeloid leukaemia 1 (AML1) protein belongs to the Runx family of transcription factors and is crucial for haematopoietic development. The genes encoding Runx1 and its associated factor CBF beta are the most frequent targets for chromosomal rearrangements in acute human leukaemias. In addition, point mutations of Runx1 in acute leukaemias and in the familial platelet disorder FPD/AML cluster within the evolutionary conserved runt domain that binds both DNA and CBF beta. Here, the crystallization of the Runx1 runt domain is reported. Crystals belong to space groups C2 and R32 and diffract to 1.7 and 2.0 A resolution, respectively.

  • 4.
    Bäckström, Stefan
    et al.
    Umeå University, Faculty of Science and Technology, Umeå Centre for Molecular Pathogenesis (UCMP) (Faculty of Science and Technology).
    Wolf-Watz, Magnus
    Chemistry.
    Grundström, Christine
    Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Härd, Torleif
    Grundström, Thomas
    Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Sauer, Uwe
    Umeå University, Faculty of Science and Technology, Umeå Centre for Molecular Pathogenesis (UCMP) (Faculty of Science and Technology).
    The RUNX1 Runt domain at 1.25A resolution: a structural switch and specifically bound chloride ions modulate DNA binding.2002In: J Mol Biol, ISSN 0022-2836, Vol. 322, no 2, p. 259-72Article in journal (Refereed)
    Abstract [en]

    The evolutionarily conserved Runt homology domain is characteristic of the RUNX family of heterodimeric eukaryotic transcription factors, including RUNX1, RUNX2 and RUNX3. The genes for RUNX1, also termed acute myeloid leukemia protein 1, AML1, and its dimerization partner core-binding factor beta, CBFbeta, are essential for hematopoietic development and are together the most common targets for gene rearrangements in acute human leukemias. Here, we describe the crystal structure of the uncomplexed RUNX1 Runt domain at 1.25A resolution and compare its conformation to previously published structures in complex with DNA, CBFbeta or both. We find that complex formation induces significant structural rearrangements in this immunoglobulin (Ig)-like DNA-binding domain. Most pronounced is the movement of loop L11, which changes from a closed conformation in the free Runt structure to an open conformation in the CBFbeta-bound and DNA-bound forms. This transition, which we refer to as the S-switch, and accompanying structural movements that affect other parts of the Runt domain are crucial for sustained DNA binding. The closed to open transition can be induced by CBFbeta alone; suggesting that one role of CBFbeta is to trigger the S-switch and to stabilize the Runt domain in a conformation enhanced for DNA binding.A feature of the Runt domain hitherto unobserved in any Ig-like DNA-binding domain is the presence of two specifically bound chloride ions. One chloride ion is coordinated by amino acid residues that make direct DNA contact. In a series of electrophoretic mobility-shift analyses, we demonstrate a chloride ion concentration-dependent stimulation of the DNA-binding activity of Runt in the physiological range. A comparable DNA-binding stimulation was observed for negatively charged amino acid residues. This suggests a regulatory mechanism of RUNX proteins through acidic amino acid residues provided by activation domains during cooperative interaction with other transcription factors.

  • 5.
    Carius, Anke B.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Rogne, Per
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Duchoslav, Miloš
    Charles University, Prague, Czech Republic.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Samuelsson, Göran
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Shutova, Tatiana
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.
    Dynamic pH‐induced conformational changes of the PsbO protein in the fluctuating acidity of the thylakoid lumen2019In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 166, no 1, p. 288-299Article in journal (Refereed)
    Abstract [en]

    The PsbO protein is an essential extrinsic subunit of photosystem II, the pigment–protein complex responsible for light‐driven water splitting. Water oxidation in photosystem II supplies electrons to the photosynthetic electron transfer chain and is accompanied by proton release and oxygen evolution. While the electron transfer steps in this process are well defined and characterized, the driving forces acting on the liberated protons, their dynamics and their destiny are all largely unknown. It was suggested that PsbO undergoes proton‐induced conformational changes and forms hydrogen bond networks that ensure prompt proton removal from the catalytic site of water oxidation, i.e. the Mn4CaO5 cluster. This work reports the purification and characterization of heterologously expressed PsbO from green algae Chlamydomonas reinhardtii and two isoforms from the higher plant Solanum tuberosum (PsbO1 and PsbO2). A comparison to the spinach PsbO reveals striking similarities in intrinsic protein fluorescence and CD spectra, reflecting the near‐identical secondary structure of the proteins from algae and higher plants. Titration experiments using the hydrophobic fluorescence probe ANS revealed that eukaryotic PsbO proteins exhibit acid–base hysteresis. This hysteresis is a dynamic effect accompanied by changes in the accessibility of the protein's hydrophobic core and is not due to reversible oligomerization or unfolding of the PsbO protein. These results confirm the hypothesis that pH‐dependent dynamic behavior at physiological pH ranges is a common feature of PsbO proteins and causes reversible opening and closing of their β‐barrel domain in response to the fluctuating acidity of the thylakoid lumen.

  • 6. Dossena, Silvia
    et al.
    Gandini, Rosaria
    Tamma, Grazia
    Vezzoli, Valeria
    Nofziger, Charity
    Tamplenizza, Margherita
    Salvioni, Elisabetta
    Bernardinelli, Emanuele
    Meyer, Giuliano
    Valenti, Giovanna
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Fuerst, Johannes
    Paulmichl, Markus
    The molecular and functional interaction between ICLN and HSPCo38 modulates the regulation of cell volume2011In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 286, no 47, p. 40659-40670Article in journal (Refereed)
    Abstract [en]

    Identifying functional partners for protein/protein interactions can be a difficult challenge. We proposed the use of the operon structure of the Caenorhabditis elegans genome as a 'New Gene-Finding Tool' (Eichmueller et al, JBC, 2004, 279:7136) that could be functionally translated to the human system. Here we show the validity of this approach by studying the predicted functional interaction between ICln and HSPC038. In Caenorhabditis elegans, the gene encoding for the ICln homolog (icln-1) is embedded in an operon with two other genes, Nx (the human homolog of Nx is HSPC038) and Ny. ICln is a highly conserved, ubiquitously expressed multifunctional protein that plays a critical role in the regulatory volume decrease after cell swelling. Following hypotonic stress, ICln translocates from the cytosol to the plasma membrane, where it has been proposed to participate in the activation of the swelling induced chloride current (IClswell). Here we show that the interaction between human ICln and HSPC038 plays a role in volume regulation after cell swelling and that HSPC038 acts as an escort, directing ICln to the cell membrane after cell swelling and facilitating the activation of IClswell. Assessment of the NMR structure of HSPC038 showed the presence of a zinc finger motif. Moreover, NMR and additional biochemical techniques enabled us to identify the putative ICln/HSPC038 interacting sites, thereby explaining the functional interaction of both proteins on a molecular level.

  • 7. Eisenmesser, Elan Z
    et al.
    Millet, Oscar
    Labeikovsky, Wladimir
    Korzhnev, Dmitry M
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Chemistry.
    Bosco, Daryl A
    Skalicky, Jack J
    Kay, Lewis E
    Kern, Dorothee
    Intrinsic dynamics of an enzyme underlies catalysis2005In: Nature, Vol. 438, p. 117-21Article in journal (Refereed)
    Abstract [en]

    A unique feature of chemical catalysis mediated by enzymes is that the catalytically reactive atoms are embedded within a folded protein. Although current understanding of enzyme function has been focused on the chemical reactions and static three-dimensional structures, the dynamic nature of proteins has been proposed to have a function in catalysis1, 2, 3, 4, 5. The concept of conformational substates has been described6; however, the challenge is to unravel the intimate linkage between protein flexibility and enzymatic function. Here we show that the intrinsic plasticity of the protein is a key characteristic of catalysis. The dynamics of the prolyl cis–trans isomerase cyclophilin A (CypA) in its substrate-free state and during catalysis were characterized with NMR relaxation experiments. The characteristic enzyme motions detected during catalysis are already present in the free enzyme with frequencies corresponding to the catalytic turnover rates. This correlation suggests that the protein motions necessary for catalysis are an intrinsic property of the enzyme and may even limit the overall turnover rate. Motion is localized not only to the active site but also to a wider dynamic network. Whereas coupled networks in proteins have been proposed previously3, 7, 8, 9, 10, we experimentally measured the collective nature of motions with the use of mutant forms of CypA. We propose that the pre-existence of collective dynamics in enzymes before catalysis is a common feature of biocatalysts and that proteins have evolved under synergistic pressure between structure and dynamics.

  • 8.
    Esteban-Martin, Santiago
    et al.
    Joint BSC-CRG-IRB Research Programme in Computational Biology, Barcelona Supercomputing Center - BSC, Barcelona, Spain.
    Fenwick, Robert Bryn
    Joint BSC-CRG-IRB Research Programme in Computational Biology, Institute for Research in Biomedicine – IRB Barcelona, Barcelona, Spain.
    Ådén, Jörgen
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Cossins, Benjamin
    Joint BSC-CRG-IRB Research Programme in Computational Biology, Barcelona Supercomputing Center - BSC, Barcelona, Spain.
    Bertoncini, Carlos W.
    Joint BSC-CRG-IRB Research Programme in Computational Biology, Institute for Research in Biomedicine – IRB Barcelona, Barcelona, Spain.
    Guallar, Victor
    Joint BSC-CRG-IRB Research Programme in Computational Biology, Barcelona Supercomputing Center - BSC, Barcelona, Spain.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Salvatella, Xavier
    Joint BSC-CRG-IRB Research Programme in Computational Biology, Institute for Research in Biomedicine – IRB Barcelona, Barcelona, Spain.
    Correlated Inter-Domain Motions in Adenylate Kinase2014In: PloS Computational Biology, ISSN 1553-734X, E-ISSN 1553-7358, Vol. 10, no 7, p. e1003721-Article in journal (Refereed)
    Abstract [en]

    Correlated inter-domain motions in proteins can mediate fundamental biochemical processes such as signal transduction and allostery. Here we characterize at structural level the inter-domain coupling in a multidomain enzyme, Adenylate Kinase (AK), using computational methods that exploit the shape information encoded in residual dipolar couplings (RDCs) measured under steric alignment by nuclear magnetic resonance (NMR). We find experimental evidence for a multi-state equilibrium distribution along the opening/closing pathway of Adenylate Kinase, previously proposed from computational work, in which inter-domain interactions disfavour states where only the AMP binding domain is closed. In summary, we provide a robust experimental technique for study of allosteric regulation in AK and other enzymes.

  • 9.
    Frost, Stefan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Ho, Oanh
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Login, Frédéric H
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Weise, Christoph F
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wolf-Watz, Hans
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Autoproteolysis and Intramolecular Dissociation of Yersinia YscU Precedes Secretion of Its C-Terminal Polypeptide YscU CC2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 11, article id e49349Article in journal (Refereed)
    Abstract [en]

    Type III secretion system mediated secretion and translocation of Yop-effector proteins across the eukaryotic target cell membrane by pathogenic Yersinia is highly organized and is dependent on a switching event from secretion of early structural substrates to late effector substrates (Yops). Substrate switching can be mimicked in vitro by modulating the calcium levels in the growth medium. YscU that is essential for regulation of this switch undergoes autoproteolysis at a conserved N↑PTH motif, resulting in a 10 kDa C-terminal polypeptide fragment denoted YscUCC. Here we show that depletion of calcium induces intramolecular dissociation of YscUCC from YscU followed by secretion of the YscUCC polypeptide. Thus, YscUCC behaved in vivo as a Yop protein with respect to secretion properties. Further, destabilized yscU mutants displayed increased rates of dissociation of YscUCC in vitro resulting in enhanced Yop secretion in vivo at 30°C relative to the wild-type strain.These findings provide strong support to the relevance of YscUCC dissociation for Yop secretion. We propose that YscUCC orchestrates a block in the secretion channel that is eliminated by calcium depletion. Further, the striking homology between different members of the YscU/FlhB family suggests that this protein family possess regulatory functions also in other bacteria using comparable mechanisms.

  • 10. Gardino, Alexandra K
    et al.
    Villali, Janice
    Kivenson, Aleksandr
    Lei, Ming
    Liu, Ce Feng
    Steindel, Phillip
    Eisenmesser, Elan Z
    Labeikovsky, Wladimir
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Chemistry.
    Clarkson, Michael W
    Kern, Dorothee
    Transient Non-native Hydrogen Bonds Promote Activation of a Signaling Protein2009In: Cell, ISSN 0092-8674, E-ISSN 1097-4172, Vol. 139, no 6, p. 1109-18Article in journal (Refereed)
    Abstract [en]

    SummaryPhosphorylation is a common mechanism for activating proteins within signaling pathways. Yet, the molecular transitions between the inactive and active conformational states are poorly understood. Here we quantitatively characterize the free-energy landscape of activation of a signaling protein, nitrogen regulatory protein C (NtrC), by connecting functional protein dynamics of phosphorylation-dependent activation to protein folding and show that only a rarely populated, pre-existing active conformation is energetically stabilized by phosphorylation. Using nuclear magnetic resonance (NMR) dynamics, we test an atomic scale pathway for the complex conformational transition, inferred from molecular dynamics simulations (Lei et al., 2009). The data show that the loss of native stabilizing contacts during activation is compensated by non-native transient atomic interactions during the transition. The results unravel atomistic details of native-state protein energy landscapes by expanding the knowledge about ground states to transition landscapes.

  • 11.
    Gupta, Arun A.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Reinartz, Ines
    Karunanithy, Gogulan
    Spilotros, Alessandro
    Jonna, Venkateswara Rao
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Hofer, Anders
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Svergun, Dmitri I.
    Baldwin, Andrew J.
    Schug, Alexander
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Formation of a Secretion-Competent Protein Complex by a Dynamic Wrap-around Binding Mechanism2018In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 430, no 18, Part B, p. 3157-3169Article in journal (Refereed)
    Abstract [en]

    Bacterial virulence is typically initiated by translocation of effector or toxic proteins across host cell membranes. A class of gram-negative pathogenic bacteria including Yersinia pseudotuberculosis and Yersinia pestis accomplishes this objective with a protein assembly called the type III secretion system. Yersinia effector proteins (Yop) are presented to the translocation apparatus through formation of specific complexes with their cognate chaperones (Syc). In the complexes where the structure is available, the Yops are extended and wrap around their cognate chaperone. This structural architecture enables secretion of the Yop from the bacterium in early stages of translocation. It has been shown previously that the chaperone-binding domain of YopE is disordered in its isolation but becomes substantially more ordered in its wrap-around complex with its chaperone SycE. Here, by means of NMR spectroscopy, small-angle X-ray scattering and molecular modeling, we demonstrate that while the free chaperone-binding domain of YopH (YopHCBD) adopts a fully ordered and globular fold, it populates an elongated, wrap-around conformation when it engages in a specific complex with its chaperone SycH2. Hence, in contrast to YopE that is unstructured in its free state, YopH transits from a globular free state to an elongated chaperone-bound state. We demonstrate that a sparsely populated YopHCBD state has an elevated affinity for SycH2 and represents an intermediate in the formation of the protein complex. Our results suggest that Yersinia has evolved a binding mechanism where SycH2 passively stimulates an elongated YopH conformation that is presented to the type III secretion system in a secretion-competent conformation.

  • 12. Henzler-Wildman, Katherine A
    et al.
    Thai, Vu
    Lei, Ming
    Ott, Maria
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Chemistry.
    Fenn, Tim
    Pozharski, Ed
    Wilson, Mark A
    Petsko, Gregory A
    Karplus, Martin
    Hübner, Christian G
    Kern, Dorothee
    Intrinsic motions along an enzymatic reaction trajectory.2007In: Nature, Vol. 450, p. 838-44Article in journal (Refereed)
    Abstract [en]

    The mechanisms by which enzymes achieve extraordinary rate acceleration and specificity have long been of key interest in biochemistry. It is generally recognized that substrate binding coupled to conformational changes of the substrate-enzyme complex aligns the reactive groups in an optimal environment for efficient chemistry. Although chemical mechanisms have been elucidated for many enzymes, the question of how enzymes achieve the catalytically competent state has only recently become approachable by experiment and computation. Here we show crystallographic evidence for conformational substates along the trajectory towards the catalytically competent 'closed' state in the ligand-free form of the enzyme adenylate kinase. Molecular dynamics simulations indicate that these partially closed conformations are sampled in nanoseconds, whereas nuclear magnetic resonance and single-molecule fluorescence resonance energy transfer reveal rare sampling of a fully closed conformation occurring on the microsecond-to-millisecond timescale. Thus, the larger-scale motions in substrate-free adenylate kinase are not random, but preferentially follow the pathways that create the configuration capable of proficient chemistry. Such preferred directionality, encoded in the fold, may contribute to catalysis in many enzymes.

  • 13.
    Ho, Oanh
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rogne, Per
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Edgren, Tomas
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Wolf-Watz, Hans
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Login, Fréderic
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Characterization of the Ruler Protein Interaction Interface on the Substrate Specificity SwitchProtein in the Yersinia Type III Secretion System2017In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 292, no 8, p. 3299-3311Article, review/survey (Refereed)
    Abstract [en]

    Many pathogenic Gram-negative bacteria use the type III secretion system (T3SS) to deliver effector proteins into eukaryotic host cells. In Yersinia the switch to secretion of effector proteins is induced first after that intimate contact between the bacterium and its eukaryotic targetcell has been established and the T3SS proteins YscP and YscU are playing a central role in thisprocess. Here we identify the molecular details of the YscP binding site on YscU by means o fnuclear magnetic resonance (NMR) spectroscopy. The binding interface is centeredon the C-terminal domain of YscU. Disruptingthe YscU/YscP interaction by introducing point mutations at the interaction interface significantly reduced the secretion of effector proteins and HeLa cell cytotoxicity. Interestingly, the bindingof YscP to the slowly self-cleaving YscU variantP264A conferred significant protection againstauto-proteolysis. The YscP mediated inhibition of YscU auto-proteolysis suggest that the cleavage event may act as a timing switch in the regulationof early vs. late T3SS substrates. We also show that YscUC binds to the inner-rod protein YscI with a Kd of 3.8 μM and with one-to-one stoichiometry. The significant similarity between different members of the YscU, YscP, YscI families suggests that the protein-protein interactions discussed in this study are alsorelevant for other T3SS-containing Gram-negative bacteria.

  • 14.
    Horvath, Istvan
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Weise, Christoph F
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Andersson, Emma K
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Chorell, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sellstedt, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bengtsson, Christoffer
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Olofsson, Anders
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Hultgren, Scott J
    Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, United States.
    Chapman, Matthew
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Wittung-Stafshede, Pernilla
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mechanisms of Protein Oligomerization: Inhibitor of Functional Amyloids Templates α-Synuclein Fibrillation2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 7, p. 3439-3444Article in journal (Refereed)
    Abstract [en]

    Small organic molecules that inhibit functional bacterial amyloid fibers, curli, are promising new antibiotics. Here we investigated the mechanism by which the ring-fused 2-pyridone FN075 inhibits fibrillation of the curli protein CsgA. Using a variety of biophysical techniques, we found that FN075 promotes CsgA to form off-pathway, non-amyloidogenic oligomeric species. In light of the generic properties of amyloids, we tested whether FN075 would also affect the fibrillation reaction of human α-synuclein, an amyloid-forming protein involved in Parkinson's disease. Surprisingly, FN075 stimulates α-synuclein amyloid fiber formation as measured by thioflavin T emission, electron microscopy (EM), and atomic force microscopy (AFM). NMR data on (15)N-labeled α-synuclein show that upon FN075 addition, α-synuclein oligomers with 7 nm radius form in which the C-terminal 40 residues remain disordered and solvent exposed. The polypeptides in these oligomers contain β-like secondary structure, and the oligomers are detectable by AFM, EM, and size-exclusion chromatography (SEC). Taken together, FN075 triggers oligomer formation of both proteins: in the case of CsgA, the oligomers do not proceed to fibers, whereas for α-synuclein, the oligomers are poised to rapidly form fibers. We conclude that there is a fine balance between small-molecule inhibition and templation that depends on protein chemistry.

  • 15.
    Kovermann, Michael
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. University of Konstanz, Department of Chemistry, Constance, Germany.
    Grundström, Christin
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sauer-Eriksson, A. Elisabeth
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sauer, Uwe H.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Structural basis for ligand binding to an enzyme by a conformational selection pathway2017In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 114, no 24, p. 6298-6303Article in journal (Refereed)
    Abstract [en]

    Proteins can bind target molecules through either induced fit or conformational selection pathways. In the conformational selection model, a protein samples a scarcely populated high-energy state that resembles a target-bound conformation. In enzymatic catalysis, such high-energy states have been identified as crucial entities for activity and the dynamic interconversion between ground states and high-energy states can constitute the rate-limiting step for catalytic turnover. The transient nature of these states has precluded direct observation of their properties. Here, we present a molecular description of a high-energy enzyme state in a conformational selection pathway by an experimental strategy centered on NMR spectroscopy, protein engineering, and X-ray crystallography. Through the introduction of a disulfide bond, we succeeded in arresting the enzyme adenylate kinase in a closed high-energy conformation that is on-pathway for catalysis. A 1.9-angstrom X-ray structure of the arrested enzyme in complex with a transition state analog shows that catalytic side-chains are properly aligned for catalysis. We discovered that the structural sampling of the substrate free enzyme corresponds to the complete amplitude that is associated with formation of the closed and catalytically active state. In addition, we found that the trapped high-energy state displayed improved ligand binding affinity, compared with the wild-type enzyme, demonstrating that substrate binding to the high-energy state is not occluded by steric hindrance. Finally, we show that quenching of fast time scale motions observed upon ligand binding to adenylate kinase is dominated by enzyme-substrate interactions and not by intramolecular interactions resulting from the conformational change.

  • 16.
    Kovermann, Michael
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rogne, Per
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Protein dynamics and function from solution state NMR spectroscopy2016In: Quarterly reviews of biophysics (Print), ISSN 0033-5835, E-ISSN 1469-8994, Vol. 49, article id e6Article, review/survey (Refereed)
    Abstract [en]

    It is well-established that dynamics are central to protein function; their importance is implicitly acknowledged in the principles of the Monod, Wyman and Changeux model of binding cooperativity, which was originally proposed in 1965. Nowadays the concept of protein dynamics is formulated in terms of the energy landscape theory, which can be used to understand protein folding and conformational changes in proteins. Because protein dynamics are so important, a key to understanding protein function at the molecular level is to design experiments that allow their quantitative analysis. Nuclear magnetic resonance (NMR) spectroscopy is uniquely suited for this purpose because major advances in theory, hardware, and experimental methods have made it possible to characterize protein dynamics at an unprecedented level of detail. Unique features of NMR include the ability to quantify dynamics (i) under equilibrium conditions without external perturbations, (ii) using many probes simultaneously, and (iii) over large time intervals. Here we review NMR techniques for quantifying protein dynamics on fast (ps-ns), slow (μs-ms), and very slow (s-min) time scales. These techniques are discussed with reference to some major discoveries in protein science that have been made possible by NMR spectroscopy.

  • 17.
    Kovermann, Michael
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ådén, Jörgen
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Grundström, Christin
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sauer-Eriksson, A. Elisabeth
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sauer, Uwe H
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Structural basis for catalytically restrictive dynamics of a high-energy enzyme state2015In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, article id 7644Article in journal (Refereed)
    Abstract [en]

    An emerging paradigm in enzymology is that transient high-energy structural states play crucial roles in enzymatic reaction cycles. Generally, these high-energy or ‘invisible’ states cannot be studied directly at atomic resolution using existing structural and spectroscopic techniques owing to their low populations or short residence times. Here we report the direct NMR-based detection of the molecular topology and conformational dynamics of a catalytically indispensable high-energy state of an adenylate kinase variant. On the basis of matching energy barriers for conformational dynamics and catalytic turnover, it was found that the enzyme’s catalytic activity is governed by its dynamic interconversion between the high-energy state and a ground state structure that was determined by X-ray crystallography. Our results show that it is possible to rationally tune enzymes’ conformational dynamics and hence their catalytic power—a key aspect in rational design of enzymes catalysing novel reactions.

  • 18.
    Liu, Hebin
    et al.
    Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Holm, Magnus
    Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Xie, Xiao-Qi
    Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Chemistry.
    Grundström, Thomas
    Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    AML1/Runx1 recruits calcineurin to regulate granulocyte macrophage colony-stimulating factor by Ets1 activation.2004In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 279, no 28, p. 29398-29408Article in journal (Refereed)
    Abstract [en]

    Acute myeloid leukemia 1 (AML1), also denoted Runx1, is a transcription factor essential for hematopoiesis, and the AML1 gene is the most common target of chromosomal translocations in human leukemias. AML1 binds to sequences present in the regulatory regions of a number of hematopoiesis-specific genes, including certain cytokines such as granulocyte macrophage colony-stimulating factor (GM-CSF) up-regulated after T cell receptor stimulation. Here we show that both subunits of the Ca(2+)/calmodulin-dependent protein phosphatase calcineurin (CN), which is activated upon T cell receptor stimulation, interact directly with the N-terminal runt homology domain-containing part of AML1. The regulatory CN subunit binds AML1 with a higher affinity and in addition also interacts with the isolated runt homology domain. The related Runx2 transcription factor, which is essential for bone formation, also interacts with CN. A constitutively active derivative of CN is shown to activate synergistically the GM-CSF promoter/enhancer together with AML1 or Runx2. We also provide evidence that relief of the negative effect of the AML1 sites is important for Ca(2+) activation of the GM-CSF promoter/enhancer and that AML1 overexpression increases this Ca(2+) activation. Both subunits of CN interact with AML1 in coimmunoprecipitation analyses, and confocal microscopy analysis of cells expressing fluorescence-tagged protein derivatives shows that CN can be recruited to the nucleus by AML1 in vivo. Mutant analysis of the GM-CSF promoter shows that the Ets1 binding site of the promoter is essential for the synergy between AML1 and CN in Jurkat T cells. Analysis of the effects of inhibitors of the protein kinase glycogen synthase kinase-3beta and in vitro phosphorylation/dephosphorylation analysis of Ets1 suggest that glycogen synthase kinase-3beta-phosphorylated Ets1 is a target of AML1-recruited CN phosphatase at the GM-CSF promoter.

  • 19.
    Malisauskas, Mantas
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Weise, Christoph
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Yanamandra, Kiran
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Morozova-Roche, Ludmilla
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Lability landscape and protease resistance of human insulin amyloid: a new insight into its molecular properties2010In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 396, no 1, p. 60-74Article in journal (Refereed)
    Abstract [en]

    Amyloid formation is a universal behavior of proteins central to many important human pathologies and industrial processes. The extreme stability of amyloids towards chemical and proteolytic degradation is an acquired property compared to the precursor proteins and is a major prerequisite for their accumulation. Here we report a study on the lability of human insulin amyloid as a function of pH and amyloid ageing. Using a range of methods such as AFM, thioflavin-T fluorescence, circular dichroism and gas phase electrophoretic mobility macromolecule analysis we probed the propensity of human insulin amyloid to propagate or dissociate in a wide span of pHs and ageing in a low concentration regime. We generated a three-dimensional amyloid lability landscape in coordinates of pH and amyloid ageing, which displays three distinctive features: (i) a maximum propensity to grow near pH 3.8 and an age corresponding the inflection point of the growth phase; (ii) an abrupt cut-off between growth and disaggregation at pH 8-10; (iii) isoclines shifted towards older age during the amyloid growth phase at pH 4-9, reflecting the greater stability of aged amyloid. Thus, lability of amyloid strongly depends on the ionization state of insulin and on the structure and maturity of amyloid fibrils. The stability of insulin amyloid towards protease K was assessed by using real-time AFM and thioflavin-T fluorescence. We estimated that amyloid fibrils can be digested both from the free ends and within the length of the fibril with a rate of ca. 4 nm/min. Our results highlight that amyloid structures, depending on solution conditions, can be less stable than commonly perceived. These results have wide implications for understanding the propagation of amyloids via a seeding mechanism as well as for understanding their natural clearance and dissociation under solution conditions unfavorable for amyloid formation in biological systems and industrial applications.

  • 20.
    Olsson, Ulrika
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Overlap between folding and functional energy landscapes for adenylate kinase conformational change2010In: Nature communications, ISSN 2041-1723, Vol. 1, no 8, p. 111-Article in journal (Refereed)
    Abstract [en]

    Enzyme function is often dependent on fluctuations between inactive and active structural ensembles. Adenylate kinase isolated from Escherichia coli (AK(e)) is a small phosphotransfer enzyme in which interconversion between inactive (open) and active (closed) conformations is rate limiting for catalysis. AK(e) has a modular three-dimensional architecture with two flexible substrate-binding domains that interact with the substrates AMP, ADP and ATP. Here, we show by using a combination of biophysical and mutagenic approaches that the interconversion between open and closed states of the ATP-binding subdomain involves partial subdomain unfolding/refolding in an otherwise folded enzyme. These results provide a novel and, possibly general, molecular mechanism for the switch between open and closed conformations in AK(e).

  • 21. Palm, Maria E
    et al.
    Weise, Christoph F
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Lundin, Christina
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Wingsle, Gunnar
    Nygren, Yvonne
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Björn, Erik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Naredi, Peter
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wittung-Stafshede, Pernilla
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Cisplatin binds human copper chaperone Atox1 and promotes unfolding in vitro2011In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 108, no 17, p. 6951-6956Article in journal (Refereed)
    Abstract [en]

    Cisplatin (cisPt), Pt(NH(3))(2)Cl(2), is a cancer drug believed to kill cells via DNA binding and damage. Recent work has implied that the cellular copper (Cu) transport machinery may be involved in cisPt cell export and drug resistance. Normally, the Cu chaperone Atox1 binds Cu(I) via two cysteines and delivers the metal to metal-binding domains of ATP7B; the ATP7B domains then transfer the metal to the Golgi lumen for loading on cuproenzymes. Here, we use spectroscopic methods to test if cisPt interacts with purified Atox1 in solution in vitro. We find that cisPt binds to Atox1's metal-binding site regardless of the presence of Cu or not: When Cu is bound to Atox1, the near-UV circular dichroism signals indicate Cu-Pt interactions. From NMR data, it is evident that cisPt binds to the folded protein. CisPt-bound Atox1 is however not stable over time and the protein begins to unfold and aggregate. The reaction rates are limited by slow cisPt dechlorination. CisPt-induced unfolding of Atox1 is specific because this effect was not observed for two unrelated proteins that also bind cisPt. Our study demonstrates that Atox1 is a candidate for cisPt drug resistance: By binding to Atox1 in the cytoplasm, cisPt transport to DNA may be blocked. In agreement with this model, cell line studies demonstrate a correlation between Atox1 expression levels, and cisplatin resistance.

  • 22. Perdersen, Martin Nors
    et al.
    Fodera, Vito
    Horvath, Istvan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    van Maarschalkerweerd, Andreas
    Toft, Katrine Norgaard
    Weise, Christoph
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wittung-Stafshede, Pernilla
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Vestergaard, Bente
    Direct Correlation Between Ligand-Induced alpha-Synuclein Oligomers and Amyloid-like Fibril Growth2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 10422Article in journal (Refereed)
    Abstract [en]

    Aggregation of proteins into amyloid deposits is the hallmark of several neurodegenerative diseases such as Alzheimer's and Parkinson's disease. The suggestion that intermediate oligomeric species may be cytotoxic has led to intensified investigations of pre-fibrillar oligomers, which are complicated by their transient nature and low population. Here we investigate alpha-synuclein oligomers, enriched by a 2-pyridone molecule (FN075), and the conversion of oligomers into fibrils. As probed by leakage assays, the FN075 induced oligomers potently disrupt vesicles in vitro, suggesting a potential link to disease related degenerative activity. Fibrils formed in the presence and absence of FN075 are indistinguishable on microscopic and macroscopic levels. Using small angle X-ray scattering, we reveal that FN075 induced oligomers are similar, but not identical, to oligomers previously observed during alpha-synuclein fibrillation. Since the levels of FN075 induced oligomers correlate with the amounts of fibrils among different FN075: protein ratios, the oligomers appear to be on-pathway and modeling supports an 'oligomer stacking model' for alpha-synuclein fibril elongation.

  • 23.
    Rogne, Per
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Andersson, David
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Grundström, Christin
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sauer-Eriksson, Elisabeth
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Linusson, Anna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Nucleation of an Activating Conformational Change by a Cation−Π Interaction2019In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 58, no 32, p. 3408-3412Article in journal (Refereed)
    Abstract [en]

    As a key molecule in biology, adenosine triphosphate (ATP) has numerous crucial functions in, for instance, energetics, post-translational modifications, nucleotide biosynthesis, and cofactor metabolism. Here, we have discovered an intricate interplay between the enzyme adenylate kinase and its substrate ATP. The side chain of an arginine residue was found to be an efficient sensor of the aromatic moiety of ATP through the formation of a strong cation−π interaction. In addition to recognition, the interaction was found to have dual functionality. First, it nucleates the activating conformational transition of the ATP binding domain and also affects the specificity in the distant AMP binding domain. In light of the functional consequences resulting from the cation−π interaction, it is possible that the mode of ATP recognition may be a useful tool in enzyme design.

  • 24.
    Rogne, Per
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ekestubbe, Sofie
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Nordfelth, Roland
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Forsberg, Åke
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    The type III secretion regulatory proteins LcrV, LcrG and YopD, in Yersinia, form a tripartite complexManuscript (preprint) (Other academic)
  • 25.
    Rogne, Per
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rosselin, Marie
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Grundström, Christin
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hedberg, Christian
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    H. Sauer, Uwe
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Molecular mechanism of ATP versus GTP selectivity of adenylate kinase2018In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 115, no 12, p. 3012-3017Article in journal (Refereed)
    Abstract [en]

    Enzymatic substrate selectivity is critical for the precise control of metabolic pathways. In cases where chemically related substrates are present inside cells, robust mechanisms of substrate selectivity are required. Here, we report the mechanism utilized for catalytic ATP versus GTP selectivity during adenylate kinase (Adk) -mediated phosphorylation of AMP. Using NMR spectroscopy we found that while Adk adopts a catalytically competent and closed structural state in complex with ATP, the enzyme is arrested in a catalytically inhibited and open state in complex with GTP. X-ray crystallography experiments revealed that the interaction interfaces supporting ATP and GTP recognition, in part, are mediated by coinciding residues. The mechanism provides an atomic view on how the cellular GTP pool is protected from Adk turnover, which is important because GTP has many specialized cellular functions. In further support of this mechanism, a structure-function analysis enabled by synthesis of ATP analogs suggests that a hydrogen bond between the adenine moiety and the backbone of the enzyme is vital for ATP selectivity. The importance of the hydrogen bond for substrate selectivity is likely general given the conservation of its location and orientation across the family of eukaryotic protein kinases.

  • 26.
    Rogne, Per
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sparrman, Tobias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Anugwom, Ikenna
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Real-time 31P NMR investigation on the catalytic behavior of the enzyme Adenylate kinase in the matrix of a switchable ionic liquid2015In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 8, no 2, p. 3764-3768Article in journal (Refereed)
    Abstract [en]

    The integration of highly efficient enzymatic catalysis with the solvation properties of ionic liquids for an environmentally friendly and efficient use of raw materials such as wood requires fundamental knowledge about the influence of relevant ionic liquids on enzymes. Switchable ionic liquids (SIL) are promising candidates for implementation of enzymatic treatments of raw materials. One industrially interesting SIL is constituted by monoethanol amine (MEA) and 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) formed with sulfur dioxide (SO2) as the coupling media (DBU-SO2-MEASIL). It has the ability to solubilize the matrix of lignocellulosic biomass while leaving the cellulose backbone intact. Using a novel 31P  NMR-based real-time assay we show that this SIL is compatible with enzymatic catalysis because a model enzyme, adenylate kinase, retains its activity in up to at least 25 wt % of DBU-SO2-MEASIL. Thus this SIL appears suitable for, for example, enzymatic degradation of hemicellulose.

  • 27.
    Rogne, Per
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Urea-Dependent Adenylate Kinase Activation following Redistribution of Structural States2016In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 111, no 7, p. 1385-1395Article in journal (Refereed)
    Abstract [en]

    Proteins are often functionally dependent on conformational changes that allow them to sample structural states that are sparsely populated in the absence of a substrate or binding partner. The distribution of such structural microstates is governed by their relative stability, and the kinetics of their interconversion is governed by the magnitude of associated activation barriers. Here, we have explored the interplay among structure, stability, and function of a selected enzyme, adenylate kinase (Adk), by monitoring changes in its enzymatic activity in response to additions of urea. For this purpose we used a 31P NMR assay that was found useful for heterogeneous sample compositions such as presence of urea. It was found that Adk is activated at low urea concentrations whereas higher urea concentrations unfolds and thereby deactivates the enzyme. From a quantitative analysis of chemical shifts, it was found that urea redistributes preexisting structural microstates, stabilizing a substrate-bound open state at the expense of a substrate-bound closed state. Adk is rate-limited by slow opening of substrate binding domains and the urea-dependent redistribution of structural states is consistent with a model where the increased activity results from an increased rate-constant for domain opening. In addition, we also detected a strong correlation between the catalytic free energy and free energy of substrate (ATP) binding, which is also consistent with the catalytic model for Adk. From a general perspective, it appears that urea can be used to modulate conformational equilibria of folded proteins toward more expanded states for cases where a sizeable difference in solvent-accessible surface area exists between the states involved. This effect complements the action of osmolytes, such as trimethylamine N-oxide, that favor more compact protein states.

  • 28.
    Rundqvist, Louise
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ådén, Jörgen
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sparrman, Tobias
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wallgren, Marcus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Olsson, Ulrika
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Noncooperative folding of subdomains in Adenylate Kinase2009In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 48, no 9, p. 1911-1927Article in journal (Refereed)
    Abstract [en]

    Conformational change is regulating the biological activity of a large number of proteins and enzymes. Efforts in structural biology have provided molecular descriptions of the interactions that stabilize the stable ground states on the reaction trajectories during conformational change. Less is known about equilibrium thermodynamic stabilities of the polypeptide segments that participate in structural changes and whether the stabilities are relevant for the reaction pathway. Adenylate kinase (Adk) is composed of three subdomains: CORE, ATPlid, and AMPbd. ATPlid and AMPbd are flexible nucleotide binding subdomains where large-scale conformational changes are directly coupled to catalytic activity. In this report, the equilibrium thermodynamic stabilities of Adk from both mesophilic and hyperthermophilic bacteria were investigated using solution state NMR spectroscopy together with protein engineering experiments. Equilibrium hydrogen to deuterium exchange experiments indicate that the flexible subdomains are of significantly lower thermodynamic stability compared to the CORE subdomain. Using site-directed mutagenesis, parts of ATPlid and AMPbd could be selectively unfolded as a result of perturbation of hydrophobic clusters located in these respective subdomains. Analysis of the perturbed Adk variants using NMR spin relaxation and Cα chemical shifts shows that the CORE subdomain can fold independently of ATPlid and AMPbd; consequently, folding of the two flexible subdomains occurs independently of each other. Based on the experimental results it is apparent that the flexible subdomains fold into their native structure in a noncooperative manner with respect to the CORE subdomain. These results are discussed in light of the catalytically relevant conformational change of ATPlid and AMPbd.

  • 29.
    Tükenmez, Hasan
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Magnussen, Helge
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kovermann, Michael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Byström, Anders
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Linkage between Fitness of Yeast Cells and Adenylate Kinase Catalysis2016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 9, article id e0163115Article in journal (Refereed)
    Abstract [en]

    Enzymes have evolved with highly specific values of their catalytic parameters kcat and KM. This poses fundamental biological questions about the selection pressures responsible for evolutionary tuning of these parameters. Here we are address these questions for the enzyme adenylate kinase (Adk) in eukaryotic yeast cells. A plasmid shuffling system was developed to allow quantification of relative fitness (calculated from growth rates) of yeast in response to perturbations of Adk activity introduced through mutations. Biophysical characterization verified that all variants studied were properly folded and that the mutations did not cause any substantial differences to thermal stability. We found that cytosolic Adk is essential for yeast viability in our strain background and that viability could not be restored with a catalytically dead, although properly folded Adk variant. There exist a massive overcapacity of Adk catalytic activity and only 12% of the wild type kcat is required for optimal growth at the stress condition 20°C. In summary, the approach developed here has provided new insights into the evolutionary tuning of kcat for Adk in a eukaryotic organism. The developed methodology may also become useful for uncovering new aspects of active site dynamics and also in enzyme design since a large library of enzyme variants can be screened rapidly by identifying viable colonies.

  • 30.
    Wallgren, Marcus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Ådén, Jörgen
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Pylypenko, Olena
    Department of Physical Biochemistry, Max-Planck-Institute for Molecular Physiology, 44202 Dortmund, Germany.
    Mikaelsson, Therese
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Johansson, Lennart B-Å
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rak, Alexey
    Department of Physical Biochemistry, Max-Planck-Institute for Molecular Physiology, 44202 Dortmund, Germany.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Extreme temperature tolerance of a hyperthermophilic protein coupled to residual structure in the unfolded state2008In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 379, no 4, p. 845-858Article in journal (Refereed)
    Abstract [en]

    Understanding the mechanisms that dictate protein stability is of large relevance, for instance, to enable design of temperature-tolerant enzymes with high enzymatic activity over a broad temperature interval. In an effort to identify such mechanisms, we have performed a detailed comparative study of the folding thermodynamics and kinetics of the ribosomal protein S16 isolated from a mesophilic (S16meso) and hyperthermophilic (S16thermo) bacterium by using a variety of biophysical methods. As basis for the study, the 2.0 Å X-ray structure of S16thermo was solved using single wavelength anomalous dispersion phasing. Thermal unfolding experiments yielded midpoints of 59 and 111 °C with associated changes in heat capacity upon unfolding (ΔCp0) of 6.4 and 3.3 kJ mol− 1 K− 1, respectively. A strong linear correlation between ΔCp0 and melting temperature (Tm) was observed for the wild-type proteins and mutated variants, suggesting that these variables are intimately connected. Stopped-flow fluorescence spectroscopy shows that S16meso folds through an apparent two-state model, whereas S16thermo folds through a more complex mechanism with a marked curvature in the refolding limb indicating the presence of a folding intermediate. Time-resolved energy transfer between Trp and N-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-yl)methyl iodoacetamide of proteins mutated at selected positions shows that the denatured state ensemble of S16thermo is more compact relative to S16meso. Taken together, our results suggest the presence of residual structure in the denatured state ensemble of S16thermo that appears to account for the large difference in quantified ΔCp0 values and, in turn, parts of the observed extreme thermal stability of S16thermo. These observations may be of general importance in the design of robust enzymes that are highly active over a wide temperature span.

  • 31.
    Weise, Christoph F
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Login, Frédéric H
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Ho, Oanh
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Gröbner, Gerhard
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wolf-Watz, Hans
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Negatively charged lipid membranes promote a disorder-order transition in the Yersinia YscU protein2014In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 107, no 8, p. 1950-1961Article in journal (Refereed)
    Abstract [en]

    The inner membrane of Gram-negative bacteria is negatively charged, rendering positively charged cytoplasmic proteins in close proximity likely candidates for protein-membrane interactions. YscU is a Yersinia pseudotuberculosis type III secretion system protein crucial for bacterial pathogenesis. The protein contains a highly conserved positively charged linker sequence that separates membrane-spanning and cytoplasmic (YscUC) domains. Although disordered in solution, inspection of the primary sequence of the linker reveals that positively charged residues are separated with a typical helical periodicity. Here, we demonstrate that the linker sequence of YscU undergoes a largely electrostatically driven coil-to-helix transition upon binding to negatively charged membrane interfaces. Using membrane-mimicking sodium dodecyl sulfate micelles, an NMR derived structural model reveals the induction of three helical segments in the linker. The overall linker placement in sodium dodecyl sulfate micelles was identified by NMR experiments including paramagnetic relaxation enhancements. Partitioning of individual residues agrees with their hydrophobicity and supports an interfacial positioning of the helices. Replacement of positively charged linker residues with alanine resulted in YscUC variants displaying attenuated membrane-binding affinities, suggesting that the membrane interaction depends on positive charges within the linker. In vivo experiments with bacteria expressing these YscU replacements resulted in phenotypes displaying significantly reduced effector protein secretion levels. Taken together, our data identify a previously unknown membrane-interacting surface of YscUC that, when perturbed by mutations, disrupts the function of the pathogenic machinery in Yersinia.

  • 32.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Novel "order-disorder-order" mechanism for adenylate kinase conformational change2011Conference paper (Other academic)
  • 33.
    Wolf-Watz, Magnus
    et al.
    Umeå University, Faculty of Science and Technology, Chemistry.
    Bäckström, Stefan
    Umeå Centre for Molecular Pathogenesis (UCMP) (Faculty of Science and Technology).
    Grundström, Thomas
    Faculty of Medicine, Molecular Biology (Faculty of Medicine).
    Sauer, Uwe
    Umeå Centre for Molecular Pathogenesis (UCMP) (Faculty of Science and Technology).
    Härd, Torleif
    Chloride binding by the AML1/Runx1 transcription factor studied by NMR2001In: FEBS Letters, ISSN 0014-5793, Vol. 488, no 1-2, p. 81-4Article in journal (Refereed)
    Abstract [en]

    It is known that the DNA binding Runt domain of the AML1/Runx1 transcription factor coordinates Cl(-) ions. In this paper we have determined Cl(-) binding affinities of AML1 by (35)Cl nuclear magnetic resonance (NMR) linewidth analysis. The Runt domain binds Cl(-) with a dissociation constant (K(d,Cl)) of 34 mM. If CBFbeta is added to form a 1:1 complex, the K(d,Cl) value increases to 56 mM. Homology modeling suggests that a high occupancy Cl(-) binding site overlaps with the DNA binding surface. NMR data show that DNA displaces this Cl(-) ion. Possible biological roles of Cl(-) binding are discussed based on these findings.

  • 34.
    Wolf-Watz, Magnus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Kovermann, Michael
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Dynamics of a Naturally Hidden State Restricts Adenylate Kinase Activity2015In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 108, no 2, p. 30A-30AArticle in journal (Other academic)
  • 35.
    Wolf-Watz, Magnus
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Rogne, Per
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sauer-Eriksson, A. Elisabeth
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Sauer, Uwe H.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Hedberg, Christian
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Positive and Negative Substrate Interference Supported by Coinciding Enzyme Residues2019In: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 116, no 3, p. 485A-485AArticle in journal (Other academic)
  • 36.
    Wolf-Watz, Magnus
    et al.
    Umeå University, Faculty of Science and Technology, Chemistry.
    Thai, Vu
    Henzler-Wildman, Katherine
    Hadjipavlou, Georgia
    Eisenmesser, Elan Z
    Kern, Dorothee
    Linkage between dynamics and catalysis in a thermophilic-mesophilic enzyme pair2004In: Nature Structural & Molecular Biology, Vol. 11, p. 945-9Article in journal (Refereed)
    Abstract [en]

    A fundamental question is how enzymes can accelerate chemical reactions. Catalysis is not only defined by actual chemical steps, but also by enzyme structure and dynamics. To investigate the role of protein dynamics in enzymatic turnover, we measured residue-specific protein dynamics in hyperthermophilic and mesophilic homologs of adenylate kinase during catalysis. A dynamic process, the opening of the nucleotide-binding lids, was found to be rate-limiting for both enzymes as measured by NMR relaxation. Moreover, we found that the reduced catalytic activity of the hyperthermophilic enzyme at ambient temperatures is caused solely by a slower lid-opening rate. This comparative and quantitative study of activity, structure and dynamics revealed a close link between protein dynamics and catalytic turnover.

  • 37.
    Ådén, Jörgen
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Verma, Abhinav
    Schug, Alexander
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Modulation of a pre-existing conformational equilibrium tunes adenylate kinase activity2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 40, p. 16562-16570Article in journal (Refereed)
    Abstract [en]

    Structural plasticity is often required for distinct microscopic steps during enzymatic reaction cycles. Adenylate kinase from Escherichia coli (AKeco) populates two major conformations in solution; the open (inactive) and closed (active) state, and the overall turn-over rate is inversely proportional to the life-time of the active conformation. Therefore, structural plasticity is intimately cou-pled to enzymatic turn-over in AKeco. Here we probe the open to closed conformational equilibrium in the absence of bound substrate with NMR spectroscopy and molecular dynamics simulations. The conformational equilibrium in absence of substrate, and in turn, the turn-over number can be modulated with mutational- and osmolyte-driven perturbations. Removal of one hydrogen bond between the ATP and AMP binding sub-domains results in a population shift towards the open conformation and a resulting increase of kcat. Addition of the osmolyte TMAO to AKeco results in population shift towards the closed conformation and a significant reduction of kcat. The Michaelis constants (KM) scale with the change in kcat, which follows from the influence of the population of the closed conformation for substrate binding affinity. Hence, kcat and KM are mutually dependent and, in the case of AKeco, any perturbation that modulates kcat is mirrored with a proportional response in KM. Thus, our results demonstrate that the equilibrium constant of a pre-existing conformational equilibrium directly affect enzymatic catalysis. From an evolutionary perspective our findings suggests that, for AKeco, there exists ample flexibility to obtain a specificity constant (kcat/KM) that commensurate with the exerted cellular selective pressure.

  • 38.
    Ådén, Jörgen
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wallgren, Marcus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Storm, Patrik
    Weise, Christoph
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Christiansen, Alexander
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Schröder, Wolfgang
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Funk, Christiane
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Arabidopsis thaliana peroxiredoxin Q is extraordinarily dynamic on the μs-ms timescaleManuscript (preprint) (Other academic)
    Abstract [en]

    Peroxiredoxin Q (PrxQ) isolated from Arabidopsis thaliana belongs to a family of redox enzymes called peroxiredoxins, which are thioredoxin- or glutaredoxin dependent peroxidases acting to reduce peroxides and in particular hydrogen peroxide. PrxQ cycles between an active reduced state and an inactive oxidized state during its catalytic cycle. The catalytic mechanism involves a nucleophilic attack of the catalytic cysteine on hydrogen peroxide to generate a sulfonic acid intermediate with a concerted release of a water molecule. This intermediate is subsequently relaxed by the reaction of a second cysteine, denoted as the resolving cysteine, generating an intermolecular disulphide bond to expel a second water molecule into solution. PrxQ is finally recycled to the active state by a thioredoxin dependent reduction. Previous structural studies of PrxQ homologues have provided the structural basis for the switch between reduced and oxidized conformations. Here we have performed a detailed study of the structure and dynamics of PrxQ in both the oxidized and reduced state. Reliable and experimentally validated structural models of PrxQ in both oxidation states were generated using homology based modeling. Model-free analyses of NMR spin relaxation show that PrxQ is monomeric in both oxidation states. As evident from fast R2 relaxation rates the reduced form of PrxQ undergoes unprecedented dynamics on the slow μs-ms timescale. The ground state of the conformational dynamics is likely the stably folded reduced state as implied by circular dichroism spectroscopy. We speculate that the extensive dynamics is intimately related to the catalytic function of PrxQ.

  • 39.
    Ådén, Jörgen
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wallgren, Marcus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Storm, Patrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Weise, Christoph
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Christiansen, Alexander
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Schröder, Wolfgang P
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Funk, Christiane
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Extraordinary μs-ms backbone dynamics in Arabidopsis thaliana peroxiredoxin Q2011In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1814, no 12, p. 1880-1890Article in journal (Refereed)
    Abstract [en]

    Peroxiredoxin Q (PrxQ) isolated from Arabidopsis thaliana belongs to a family of redox enzymes called peroxiredoxins, which are thioredoxin- or glutaredoxin-dependent peroxidases acting to reduce peroxides and in particular hydrogen peroxide. PrxQ cycles between an active reduced state and an inactive oxidized state during its catalytic cycle. The catalytic mechanism involves a nucleophilic attack of the catalytic cysteine on hydrogen peroxide to generate a sulfonic acid intermediate with a concerted release of a water molecule. This intermediate is subsequently relaxed by the reaction of a second cysteine, denoted the resolving cysteine, generating an intramolecular disulfide bond and release of a second water molecule. PrxQ is recycled to the active state by a thioredoxin-dependent reduction. Previous structural studies of PrxQ homologues have provided the structural basis for the switch between reduced and oxidized conformations. Here, we have performed a detailed study of the activity, structure and dynamics of PrxQ in both the oxidized and reduced states. Reliable and experimentally validated structural models of PrxQ in both oxidation states were generated using homology based modeling. Analysis of NMR spin relaxation rates shows that PrxQ is monomeric in both oxidized and reduced states. As evident from R(2) relaxation rates the reduced form of PrxQ undergoes unprecedented dynamics on the slow μs-ms timescale. The ground state of this conformational dynamics is likely the stably folded reduced state as implied by circular dichroism spectroscopy. We speculate that the extensive dynamics is intimately related to the catalytic function of PrxQ.

  • 40.
    Ådén, Jörgen
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Weise, Christoph
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Brännström, Kristoffer
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Olofsson, Anders
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Structural topology and activation of an initial adenylate kinase-substrate complex2013In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 52, no 6, p. 1055-1061Article in journal (Refereed)
    Abstract [en]

    Enzymatic activity is ultimately defined by the structure, chemistry and dynamics of the Michaelis complex. There exist a large number of experimentally determined structures between enzymes and substrates or substrate analogues or inhibitors. However, transient, short-lived encounter and equilibrium structures also play fundamental roles during enzymatic reaction cycles. Such structures are inherently difficult to study with conventional experimental techniques. The enzyme adenylate kinase undergoes major conformational rearrangements in response to binding of its substrates ATP and AMP. ATP is sandwiched between two binding surfaces in the closed and active enzyme conformation. Thus, ade-nylate kinase harbors two spatially distant surfaces in the substrate free open conformation of which one is responsible for the initial interaction with ATP. Here, we have performed primarily nuclear magnetic resonance experiments on Escherichia coli adenylate kinase (AKeco) variants that enabled identification of the site responsible for the initial ATP interaction. This allowed a characterization of the structural topology of an initial equilibrium complex between AKeco and ATP. Based on the results it is suggested that the ATP binding mechanism to AKeco is a mixture between "induced fit" and "conformational selection" models. It is shown that ATP is activated in the initial enzyme bound complex since it displays an appreciable rate of non-productive ATP hydrolysis. In summary our results provide novel structural and functional insights into adenylate kinase catalysis.

  • 41.
    Ådén, Jörgen
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    NMR identification of transient complexes critical to adenylate kinase catalysis2007In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 129, no 45, p. 14003-12Article in journal (Refereed)
    Abstract [en]

    A fundamental question in protein chemistry is how the native energy landscape of enzymes enables efficient catalysis of chemical reactions. Adenylate kinase is a small monomeric enzyme that catalyzes the reversible conversion of AMP and ATP into two ADP molecules. Previous structural studies have revealed that substrate binding is accompanied by large rate-limiting spatial displacements of both the ATP and AMP binding motifs. In this report a solution-state NMR approach was used to probe the native energy landscape of adenylate kinase in its free form, in complex with its natural substrates, and in the presence of a tight binding inhibitor. Binding of ATP induces a dynamic equilibrium in which the ATP binding motif populates both the open and the closed conformations with almost equal populations. A similar scenario is observed for AMP binding, which induces an equilibrium between open and closed conformations of the AMP binding motif. These ATP- and AMP-bound structural ensembles represent complexes that exist transiently during catalysis. Simultaneous binding of AMP and ATP is required to force both substrate binding motifs to close cooperatively. In addition, a previously unknown unidirectional energetic coupling between the ATP and AMP binding sites was discovered. On the basis of these and previous results, we propose that adenylate kinase belongs to a group of enzymes whose substrates act to shift pre-existing equilibria toward catalytically active states.

  • 42.
    Österberg, Sofia
    et al.
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Åberg, Anna
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Herrera Seitz, M. Karina
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Wolf-Watz, Magnus
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Shingler, Victoria
    Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology).
    Genetic dissection of a motility-associated c-di-GMP signalling protein of Pseudomonas putida2013In: Environmental Microbiology Reports, ISSN 1758-2229, E-ISSN 1758-2229, Vol. 5, no 4, p. 556-565Article in journal (Refereed)
    Abstract [en]

    Lack of the Pseudomonas putidaPP2258 protein or its overexpression results in defective motility on solid media. The PP2258 protein is tripartite, possessing a PAS domain linked to two domains associated with turnover of c-di-GMP - a cyclic nucleotide that controls the switch between motile and sessile lifestyles. The second messenger c-di-GMP is produced by diguanylate cyclases and degraded by phosphodiesterases containing GGDEF and EAL or HD-GYP domains respectively. It is common for enzymes involved in c-di-GMP signalling to contain two domains with potentially opposing c-di-GMP turnover activities; however, usually one is degenerate and has been adopted to serve regulatory functions. Only a few proteins have previously been found to have dual enzymatic activities - being capable of both synthesizing and hydrolysing c-di-GMP. Here, using truncated and mutant derivatives of PP2258, we show that despite a lack of complete consensus in either the GGDEF or EAL motifs, the two c-di-GMP turnover domains can function independently of each other, and that the diguanylate cyclase activity is regulated by an inhibitory I-site within its GGDEF domain. Thus, motility-associated PP2258 can be added to the short list of bifunctional c-di-GMP signalling proteins.

1 - 42 of 42
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