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  • 1.
    Bonde, Mari
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Olofsson, Annelie
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Frost, Mikaela
    Jegerschöld, Caroline
    Karolinska Institutet, Sweden.
    Bergström, Sven
    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).
    Sandblad, Linda
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Structural analysis of the B. burgdorferi integral outer membrane protein, P13, in lipid bilayer NanodiscsManuscript (preprint) (Other (popular science, discussion, etc.))
  • 2.
    Javadi, Ala
    et al.
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Söderholm, Niklas
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Olofsson, Annelie
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Flärdh, Klas
    Sandblad, Linda
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Assembly mechanisms of the bacterial cytoskeletal protein FilP2019In: Life Science Alliance, ISSN 2575-1077, Vol. 2, no 3, article id e201800290Article in journal (Refereed)
    Abstract [en]

    Despite low-sequence homology, the intermediate filament (IF)–like protein FilP from Streptomyces coelicolor displays structural and biochemical similarities to the metazoan nuclear IF lamin. FilP, like IF proteins, is composed of central coiled-coil domains interrupted by short linkers and flanked by head and tail domains. FilP polymerizes into repetitive filament bundles with paracrystalline properties. However, the cations Na+ and K+ are found to induce the formation of a FilP hexagonal meshwork with the same 60-nm repetitive unit as the filaments. Studies of polymerization kinetics, in combination with EM techniques, enabled visualization of the basic building block — a transiently soluble rod-shaped FilP molecule—and its assembly into protofilaments and filament bundles. Cryoelectron tomography provided a 3D view of the FilP bundle structure and an original assembly model of an IF-like protein of prokaryotic origin, thereby enabling a comparison with the assembly of metazoan IF.

  • 3.
    Olofsson, Annelie
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Helicobacter pylori outer membrane vesicles and the host-pathogen interaction2013Doctoral thesis, comprehensive summary (Other academic)
  • 4.
    Olofsson, Annelie
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Bäckström, AnnaUmeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.Petzold, KatjajUmeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.Gröbner, GerhardUmeå University, Faculty of Science and Technology, Department of Chemistry.Wai, SNUmeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).Carlsson, SvenUmeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.Schleucher, JürgenUmeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.Arnqvist, AnnaUmeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Helicobacter pylori outer membrane vesicles and properties for intimate host interactions2007Conference proceedings (editor) (Refereed)
  • 5.
    Olofsson, Annelie
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Nygård Skalman, Lars
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Obi, Ikenna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Lundmark, Richard
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Arnqvist, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Uptake of Helicobacter pylori vesicles is facilitated by clathrin-dependent and clathrin-independent endocytic pathways2014In: mBio, ISSN 2161-2129, E-ISSN 2150-7511, Vol. 5, no 3, p. e00979-14-Article in journal (Refereed)
    Abstract [en]

    UNLABELLED: Bacteria shed a diverse set of outer membrane vesicles that function as transport vehicles to deliver effector molecules and virulence factors to host cells. Helicobacter pylori is a gastric pathogen that infects half of the world's population, and in some individuals the infection progresses into peptic ulcer disease or gastric cancer. Here we report that intact vesicles from H. pylori are internalized by clathrin-dependent endocytosis and further dynamin-dependent processes, as well as in a cholesterol-sensitive manner. We analyzed the uptake of H. pylori vesicles by gastric epithelial cells using a method that we refer to as quantification of internalized substances (qIS). The qIS assay is based on a near-infrared dye with a cleavable linker that enables the specific quantification of internalized substances after exposure to reducing conditions. Both chemical inhibition and RNA interference in combination with the qIS assay showed that H. pylori vesicles enter gastric epithelial cells via both clathrin-mediated endocytosis and additional endocytic processes that are dependent on dynamin. Confocal microscopy revealed that H. pylori vesicles colocalized with clathrin and dynamin II and with markers of subsequent endosomal and lysosomal trafficking. Interestingly, however, knockdown of components required for caveolae had no significant effect on internalization and knockdown of components required for clathrin-independent carrier (CLIC) endocytosis increased internalization of H. pylori vesicles. Furthermore, uptake of vesicles by both clathrin-dependent and -independent pathways was sensitive to depletion, but not sequestering, of cholesterol in the host cell membrane suggesting that membrane fluidity influences the efficiency of H. pylori vesicle uptake.

    IMPORTANCE: Bacterial vesicles act as long-distance tools to deliver toxins and effector molecules to host cells. Vesicles can cause a variety of host cell responses via cell surface-induced cell signaling or internalization. Vesicles of diverse bacterial species enter host cells via different endocytic pathways or via membrane fusion. With the combination of a fluorescence-based quantification assay that quantifies internalized vesicles in a large number of cells and either chemical inhibition or RNA interference, we show that clathrin-mediated endocytosis is the major pathway for uptake of Helicobacter pylori vesicles and that lipid microdomains of the host cell membrane affect uptake of vesicles via clathrin-independent pathways. Our results provide important insights about membrane fluidity and its important role in the complex process that directs the H. pylori vesicle to a specific endocytic pathway. Understanding the mechanisms that operate in vesicle-host interactions is important to fully recognize the impact of vesicles in pathogenesis.

  • 6.
    Olofsson, Annelie
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Vallström, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Petzold, Katja
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Carlsson, Sven
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Haas, Rainer
    Max-von-Pettenkofer-Institute of Hygiene and Medical Microbiology, Dept of Bacteriology, Munich, Germany.
    Backert, Steffen
    School of Biomolecular and Biomedical Sciences, University College Dublin, Ireland.
    Nyunt Wai, Sun
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Gröbner, Gerhard
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Arnqvist, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Characterization of Helicobacter pylori vesicles and their cognate properties for intimate host interactionsManuscript (preprint) (Other academic)
  • 7.
    Olofsson, Annelie
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Vallström, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics. Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Petzold, Katja
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Tegtmeyer, Nicole
    Schleucher, Jürgen
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Carlsson, Sven
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Haas, Rainer
    Backert, Steffen
    Wai, Sun Nyunt
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Gröbner, Gerhard
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Arnqvist, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Biochemical and functional characterization of Helicobacter pylori vesicles2010In: Molecular Microbiology, ISSN 0950-382X, E-ISSN 1365-2958, Vol. 77, no 6, p. 1539-1555Article in journal (Refereed)
    Abstract [en]

    Helicobacter pylori can cause peptic ulcer disease and/or gastric cancer. Adhesion of bacteria to the stomach mucosa is an important contributor to the vigor of infection and resulting virulence. H. pylori adheres primarily via binding of BabA adhesins to ABO/Lewis b (Leb) blood group antigens and the binding of SabA adhesins to sialyl-Lewis x/a (sLex/a) antigens. Similar to most Gram-negative bacteria, H. pylori continuously buds off vesicles and vesicles derived from pathogenic bacteria often include virulence-associated factors. Here we biochemically characterized highly purified H. pylori vesicles. Major protein and phospholipid components associated with the vesicles were identified with mass spectroscopy and NMR. A subset of virulence factors present was confirmed by immunoblots. Additional functional and biochemical analysis focused on the vesicle BabA and SabA adhesins and their respective interactions to human gastric epithelium. Vesicles exhibit heterogeneity in their protein composition, which were specifically studied in respect to the BabA adhesin. We also demonstrate that the oncoprotein, CagA, is associated with the surface of H. pylori vesicles. Thus, we have explored mechanisms for intimate H. pylori vesicle-host interactions and found that the vesicles carry effector-promoting properties that are important to disease development.

  • 8.
    Petzold, Katja
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Olofsson, Annelie
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Arnqvist, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Gröbner, Gerhard
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Jürgen, Schleucher
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Semiconstant-Time P,H-COSY NMR: Analysis of Complex Mixtures of Phospholipids Originating from Helicobacter pylori2009In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 40, p. 14150-1Article in journal (Refereed)
    Abstract [en]

    Lipids play a central role in numerous biological events, ranging from normal physiological processes to host−pathogen interactions. The proposed semiconstant-time 31P,1H−COSY NMR experiment provides identification of known and structural characterization of unknown phospholipids in complex membrane extracts with high sensitivity, based on the combination of their 1H and 31P chemical shifts and coupling patterns. Furthermore, the spectra allow quantification of phospholipid composition. Analysis of the phospholipid composition of Helicobacter pylori, the causative agent of peptic ulcer disease, showed the presence of uncommon phospholipids. This novel NMR approach allows the study of changes in membrane composition in response to biological stimuli and opens up the possibility of identifying soluble phosphorus species in a number of research fields.

  • 9.
    Rajan, Anandi
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Persson, B. David
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Frängsmyr, Lars
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Olofsson, Annelie
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Sandblad, Linda
    Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
    Heino, Jyrki
    Department of Biochemistry, University of Turku, Finland.
    Takada, Yoshikazu
    Department of Dermatology, Biochemistry and Molecular Medicine, UC Davis School of Medicine, California, USA.
    Mould, A. Paul
    Biomolecular Analysis Core Facility, Faculty of Biology, Medicine and Health, University of Manchester, United Kingdom.
    Schnapp, Lynn M.
    Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, Medical University of South Carolina, Charleston, USA.
    Gall, Jason
    Vaccine Research Center (VRC), NIAID, NIH, Bethesda, USA.
    Arnberg, Niklas
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Virology. Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
    Enteric species F human adenoviruses use laminin-binding integrins as co-receptors for infection of Ht-29 cells2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, no 1, article id 10019Article in journal (Refereed)
    Abstract [en]

    The enteric species F human adenovirus types 40 and 41 (HAdV-40 and -41) are the third most common cause of infantile gastroenteritis in the world. Knowledge about HAdV-40 and -41 cellular infection is assumed to be fundamentally different from that of other HAdVs since HAdV-40 and -41 penton bases lack the αV-integrin-interacting RGD motif. This motif is used by other HAdVs mainly for internalization and endosomal escape. We hypothesised that the penton bases of HAdV-40 and -41 interact with integrins independently of the RGD motif. HAdV-41 transduction of a library of rodent cells expressing specific human integrin subunits pointed to the use of laminin-binding α2-, α3- and α6-containing integrins as well as other integrins as candidate co-receptors. Specific laminins prevented internalisation and infection, and recombinant, soluble HAdV-41 penton base proteins prevented infection of human intestinal HT-29 cells. Surface plasmon resonance analysis demonstrated that HAdV-40 and -41 penton base proteins bind to α6-containing integrins with an affinity similar to that of previously characterised penton base:integrin interactions. With these results, we propose that laminin-binding integrins are co-receptors for HAdV-40 and -41.

  • 10. Turkina, Maria V.
    et al.
    Olofsson, Annelie
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Magnusson, Karl-Eric
    Arnqvist, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Vikstrom, Elena
    Helicobacter pylori vesicles carrying CagA localize in the vicinity of cell-cell contacts and induce histone H1 binding to ATP in epithelial cells2015In: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 362, no 11, article id fnv076Article in journal (Refereed)
    Abstract [en]

    Helicobacter pylori produces outer membrane vesicles (OMV), delivering bacterial substances including the oncogenic cytotoxin-associated CagA protein to their surroundings. We investigated the effects of H. pylori OMV carrying CagA (OMV-CagA) on cell junctions and ATP-binding proteome of epithelial monolayers, using proteomics, mass spectrometry and imaging. OMV-CagA localized in close vicinity of ZO-1 tight junction protein and induced histone H1 binding to ATP. We suggest the expression of novel events in the interactions between H. pylori OMV and epithelia, which may have an influence on host gene transcription and lead to different outcomes of an infection and development of cancer.

  • 11.
    Åberg, Anna
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Gideonsson, Pär
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Vallström, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Olofsson, Annelie
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Öhman, Carina
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Rakhimova, Lena
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Borén, Thomas
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Engstrand, Lars
    Brännström, Kristoffer
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Arnqvist, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    A Repetitive DNA Element Regulates Expression of the Helicobacter pylori Sialic Acid Binding Adhesin by a Rheostat-like Mechanism2014In: PLoS Pathogens, ISSN 1553-7366, E-ISSN 1553-7374, Vol. 10, no 7, article id e1004234Article in journal (Refereed)
    Abstract [en]

    During persistent infection, optimal expression of bacterial factors is required to match the ever-changing host environment. The gastric pathogen Helicobacter pylori has a large set of simple sequence repeats (SSR), which constitute contingency loci. Through a slipped strand mispairing mechanism, the SSRs generate heterogeneous populations that facilitate adaptation. Here, we present a model that explains, in molecular terms, how an intergenically located T-tract, via slipped strand mispairing, operates with a rheostat-like function, to fine-tune activity of the promoter that drives expression of the sialic acid binding adhesin, SabA. Using T-tract variants, in an isogenic strain background, we show that the length of the T-tract generates multiphasic output from the sabA promoter. Consequently, this alters the H. pylori binding to sialyl-Lewis x receptors on gastric mucosa. Fragment length analysis of post-infection isolated clones shows that the T-tract length is a highly variable feature in H. pylori. This mirrors the host-pathogen interplay, where the bacterium generates a set of clones from which the best-fit phenotypes are selected in the host. In silico and functional in vitro analyzes revealed that the length of the T-tract affects the local DNA structure and thereby binding of the RNA polymerase, through shifting of the axial alignment between the core promoter and UP-like elements. We identified additional genes in H. pylori, with T- or A-tracts positioned similar to that of sabA, and show that variations in the tract length likewise acted as rheostats to modulate cognate promoter output. Thus, we propose that this generally applicable mechanism, mediated by promoter-proximal SSRs, provides an alternative mechanism for transcriptional regulation in bacteria, such as H. pylori, which possesses a limited repertoire of classical trans-acting regulatory factors.

  • 12.
    Öhman, Carina
    et al.
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Vallström, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics. Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Olofsson, Annelie
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Johansson, Pär
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Larsson, Christer
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Aspholm, Marina
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Arnqvist, Anna
    Umeå University, Faculty of Medicine, Department of Medical Biochemistry and Biophysics.
    Phase variation and expression mechanisms of the sialic acid binding adhesin SabA in Helicobacter pyloriManuscript (preprint) (Other academic)
    Abstract [en]

    Bacterial attachment to host epithelial surfaces by means of bacterial adhesion proteins is a key event in colonization. Phase variation is a mechanism used by bacteria that mediates frequent and reversible gains and losses in expression of proteins. In the inflamed stomach, H. pylori adherence to sialyl Lewis antigens (sLex) is mediated by the sialic acid binding adhesin (SabA). Instability in sLex-binding was previously reported and here we show that this is caused by the high frequency of ON/OFF switching in SabA expression. Our data shows that SabA phase variation is due to slippages in the number of CT repeat sequences in the 5’ end of the sabA gene (i.e. slipped strand mispairing). The sabA operon was defined and the sabA transcriptional start site was determined. Changes in the number of thymine bases present in a mononucleotide stretch upstream of the sabA gene and in close proximity to a -35-like promoter element did not affect the ON/OFF phase variation. Instead, we show that changes in intrinsic DNA properties are likely to influence SabA expression. The effect of growth phase on sLex-binding properties and SabA expression was also analyzed. SabA expression and sLex-binding increased as H. pylori entered late logarithmic phase. Our data show the ability of H. pylori to cycle between an adherent and non-adherent phenotype by phase variation mechanisms and adjustment of receptor binding activity. These data increase our understanding of how H. pylori adjust adherence properties during persistent infection.

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