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  • 1.
    Andersson, Magnus
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Kemi.
    Uhlin, Bernt Eric
    Umeå universitet, Medicinsk fakultet, Molekylärbiologi (Medicinska fakulteten).
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Physical Properties of Biopolymers Assessed by Optical Tweezers: Analysis of folding and refolding of bacterial pili2008Ingår i: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 9, nr 2, s. 221-235Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bacterial adhesion to surfaces mediated by specific adhesion organelles that promote infections, as exemplified by the pili of uropathogenic E. coli, is studied mostly at the level of cell-cell interactions and thereby reflects the averaged behavior of multiple pili. The role of pilus rod structure has therefore only been estimated from the outcome of experiments involving large numbers of organelles at the same time. It has, however, lately become clear that the biomechanical behavior of the pilus shafts play an important, albeit hitherto rather unrecognized, role in the adhesion process. For example, it has been observed that shafts from two different strains, even though they are similar in structure, result in large differences in the ability of the bacteria to adhere to their host tissue. However, in order to identify all properties of pilus structures that are of importance in the adhesion process, the biomechanical properties of pili must be assessed at the single-molecule level. Due to the low range of forces of these structures, until recently it was not possible to obtain such information. However, with the development of force-measuring optical tweezers (FMOT) with force resolution in the low piconewton range, it has lately become possible to assess forces mediated by individual pili on single living bacteria in real time. FMOT allows for a more or less detailed mapping of the biomechanical properties of individual pilus shafts, in particular those that are associated with their elongation and contraction under stress. This Mi- nireview presents the FMOT technique, the biological model system, and results from assessment of the biomechanical properties of bacterial pili. The information retrieved is also compared with that obtained by atomic force microscopy.

  • 2.
    Andersson, Magnus
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Uhlin, Bernt Eric
    Medicinsk fakultet, Molekylärbiologi (Medicinska fakulteten).
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Characterization of the mechanical properties of fimbrial structures by optical tweezers2006Ingår i: Proceedings of the VIII. Annual Linz Winter Workshop, 2006, s. 19-22Konferensbidrag (Refereegranskat)
  • 3.
    Andersson, Magnus
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Uhlin, Bernt Eric
    Umeå universitet, Medicinsk fakultet, Molekylärbiologi (Medicinska fakulteten).
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Optical tweezers for single molecule force spectroscopy on bacterial adhesion organelles2006Ingår i: Proceedings of SPIE vol. 6326: Optical Trapping and Optical Micromanipulation III, 2006, s. 632620-Konferensbidrag (Refereegranskat)
  • 4.
    Andersson, Magnus
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Characterization of S pili — investigation of their mechanical properties2007Manuskript (preprint) (Övrig (populärvetenskap, debatt, mm))
  • 5.
    Andersson, Magnus
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Uhlin, Bernt Eric
    Umeå universitet, Medicinsk fakultet, Molekylärbiologi (Medicinska fakulteten).
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    A sticky chain model of the elongation and unfolding of escherichia coli P pili under stress2006Ingår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 90, nr 5, s. 1521-1534Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A model of the elongation of P pili expressed by uropathogenic Escherichia coli exposed to stress is presented. The model is based upon the sticky chain concept, which is based upon Hooke’s law for elongation of the layer-to-layer and head-to-tail bonds between neighboring units in the PapA rod and a kinetic description of the opening and closing of bonds, described by rate equations and an energy landscape model. It provides an accurate description of the elongation behavior of P pili under stress and supports a hypothesis that the PapA rod shows all three basic stereotypes of elongation/unfolding: elongation of bonds in parallel, the zipper mode of unfolding, and elongation and unfolding of bonds in series. The two first elongation regions are dominated by a cooperative bond opening, in which each bond is influenced by its neighbor, whereas the third region can be described by individual bond opening, in which the bonds open and close randomly. A methodology for a swift extraction of model parameters from force-versus-elongation measurements performed under equilibrium conditions is derived. Entities such as the free energy, the stiffness, the elastic elongation, the opening length of the various bonds, and the number of PapA units in the rod are determined.

  • 6.
    Andersson, Magnus
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Uhlin, Bernt Eric
    Umeå universitet, Medicinsk fakultet, Molekylärbiologi (Medicinska fakulteten).
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Dynamic Force Spectroscopy of E. coli P Pili2006Ingår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 91, nr 7, s. 2717-2725Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Surface organelles (so-called pili) expressed on the bacterial membrane mediate the adhesion of Escherichia coli causing urinary tract infection. These pili possess some extraordinary elongation properties that are assumed to allow a close bacterium-to-host contact even in the presence of shear forces caused by urine flow. The elongation properties of P pili have therefore been assessed for low elongation speeds (steady-state conditions). This work reports on the behavior of P pili probed by dynamic force spectroscopy. A kinetic model for the unfolding of a helixlike chain structure is derived and verified. It is shown that the unfolding of the quaternary structure of the PapA rod takes place at a constant force that is almost independent of elongation speed for slow elongations (up to ~0.4 μm/s), whereas it shows a dynamic response with a logarithmic dependence for fast elongations. The results provide information about the energy landscape and reaction rates. The bond length and thermal bond opening and closure rates for the layer-to-layer bond have been assessed to ~0.76 nm, ~0.8 Hz, and ~8 GHz, respectively. The results also support a previously constructed sticky-chain model for elongation of the PapA rod that until now had been experimentally verified only under steady-state conditions.

  • 7.
    Andersson, Magnus
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Uhlin, Bernt Eric
    Umeå universitet, Medicinsk fakultet, Molekylärbiologi (Medicinska fakulteten).
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Force measuring optical tweezers system for long time measurements of P pili stability2006Ingår i: Proceedings of the SPIE vol. 6088: Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues IV, 2006, s. 608810-Konferensbidrag (Refereegranskat)
  • 8.
    Andersson, Magnus
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Uhlin, Bernt Eric
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Technique for determination of the number of PapA units in an E. coli P pilus2006Ingår i: Proceedings of the SPIE vol. 6088: Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues IV, 2006, s. 608814-Konferensbidrag (Refereegranskat)
  • 9.
    Andersson, Magnus
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Uhlin, Bernt Eric
    Umeå universitet, Medicinsk fakultet, Molekylärbiologi (Medicinska fakulteten).
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    The biomechanical properties of E. coli pili for urinary tract attachment reflect the host environment2007Ingår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Vol. 93, nr 9, s. 3008-3014Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Uropathogenic Escherichia coli express pili that mediate binding to host tissue cells. We demonstrate with in situ force measuring optical tweezers that the ability of P and type 1 pili to elongate by unfolding under exposure to stress is a shared property with some differences. The unfolding force of the quaternary structures under equilibrium conditions is similar, 28 ± 2 and 30 ± 2 pN for P pili and type 1 pili, respectively. However, type 1 pili are found to be more rigid than P pili through their stronger layer-to-layer bonds. It was found that type 1 pili enter a dynamic regime at elongation speeds of 6 nm/s, compared to 400 nm/s for P pili; i.e., it responds faster to an external force. This possibly helps type 1 to withstand the irregular urine flow in the urethra as compared to the more constant urine flow in the upper urinary tract. Also, it was found that type 1 pili refold during retraction at two different levels that possibly could be related to several possible configurations. Our findings highlight functions that are believed to be of importance for the bacterial ability to sustain a basic antimicrobial mechanism of the host and for bacterial colonization.

  • 10.
    Björnham, Oscar
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Ohlsson, J.
    Nilsson, U.J.
    Borén, Thomas
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Schedin, Staffan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Measurements of the binding force between the Helicobacter pylori adhesin BabA and the Lewis b blood group antigen using optical tweezers2005Ingår i: Journal of Biomedical Optics, ISSN 1560-2281 (Online), Vol. 10, nr 4, s. 044024-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Helicobacter pylori is a world-wide spread bacterium that causes persistent infections and chronic inflammations that can develop into gastritis and peptic ulcer disease. It expresses several adhesin proteins on its surface that bind to specific receptors in the gastric epithelium. The most well-known adhesin is BabA, which has previously been shown to bind specifically to the fucosylated blood group antigen Lewis b (Leb). The adhesion forces between BabA and the Leb antigen are investigated in this work and assessed by means of optical tweezers. A model system for in situ measurements of the interaction forces between individual bacteria and beads coated with Leb is developed. It is found that the de-adhesion force in this model system, measured with a loading rate of approximately 100 pNs, ranges from 20 to 200 pN. The de-adhesion force appears predominantly as multiples of an elementary force, which is determined to 25+/-1.5 pN and identified as the unbinding force of an individual BabA-Leb binding. It is concluded that adhesion in general is mediated by a small number of bindings (most often 1 to 4) despite that the contact surface between the bacterium and the bead encompassed significantly more binding sites.

  • 11.
    Castelain, Mickaël
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Sjöström, Annika E
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Uhlin, Bernt Eric
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Andersson, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Unfolding and refolding properties of S pili on extraintestinal pathogenic Escherichia coli2010Ingår i: European Biophysics Journal, ISSN 0175-7571, E-ISSN 1432-1017, Vol. 39, nr 8, s. 1105-1115Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    S pili are members of the chaperone-usher-pathway-assembled pili family that are predominantly associated with neonatal meningitis (S(II)) and believed to play a role in ascending urinary tract infections (S(I)). We used force-measuring optical tweezers to characterize the intrinsic biomechanical properties and kinetics of S(II) and S(I) pili. Under steady-state conditions, a sequential unfolding of the layers in the helix-like rod occurred at somewhat different forces, 26 pN for S(II) pili and 21 pN for S(I) pili, and there was an apparent difference in the kinetics, 1.3 and 8.8 Hz. Tests with bacteria defective in a newly recognized sfa gene (sfaX (II)) indicated that absence of the sfaX (II) gene weakens the interactions of the fimbrium slightly and decreases the kinetics. Data of S(I) are compared with those of previously assessed pili primary associated with urinary tract infections, the P and type 1 pili. S pili have weaker layer-to-layer bonds than both P and type 1 pili, 21, 28 and 30 pN, respectively. In addition, the S pili kinetics are ~10 times faster than the kinetics of P pili and ~550 times faster than the kinetics of type 1 pili. Our results also show that the biomechanical properties of pili expressed ectopically from a plasmid in a laboratory strain (HB101) and pili expressed from the chromosome of a clinical isolate (IHE3034) are identical. Moreover, we demonstrate that it is possible to distinguish, by analyzing force-extension data, the different types of pili expressed by an individual cell of a clinical bacterial isolate.

  • 12.
    Fällman, Erik
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Andersson, Magnus
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Techniques for moveable traps: The influence of aberration in optical tweezers2006Ingår i: Proceedings of the SPIE vol. 6088: Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues IV, 2006, s. 60881E-Konferensbidrag (Refereegranskat)
  • 13.
    Fällman, Erik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Andersson, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Schedin, Staffan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Jass, Jana
    Uhlin, Bernt Eric
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Dynamic properties of bacterial pili measured by optical tweezers2004Ingår i: Proceedings of SPIE - The International Society for Optical Engineering vol. 5514: Optical Trapping and Optical Micromanipulation, 2004, s. 763-773Konferensbidrag (Refereegranskat)
  • 14.
    Fällman, Erik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Schedin, Staffan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Jass, Jana
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Andersson, Magnus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Uhlin, Bernt Eric
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Optical tweezers based force measurement system for quantitating binding interactions: system design and application for the study of bacterial adhesion2004Ingår i: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 19, nr 11, s. 1429-1437Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An optical force measurement system for quantitating forces in the pN range between micrometer-sized objects has been developed. The system was based upon optical tweezers in combination with a sensitive position detection system and constructed around an inverted microscope. A trapped particle in the focus of the high numerical aperture microscope-objective behaves like an omnidirectional mechanical spring in response to an external force. The particle’s displacement from the equilibrium position is therefore a direct measure of the exerted force. A weak probe laser beam, focused directly below the trapping focus, was used for position detection of the trapped particle (a polystyrene bead). The bead and the condenser focus the light to a distinct spot in the far field, monitored by a position sensitive detector. Various calibration procedures were implemented in order to provide absolute force measurements. The system has been used to measure the binding forces between Escherichia coli bacterial adhesins and galabiose-functionalized beads

  • 15.
    Fällman, Erik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Schedin, Staffan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Jass, Jana
    Department of Microbiology and Immunology, The Lawson Health Research Institute, University of Western Ontario, London, Ontario, Canada.
    Uhlin, Bernt Eric
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    The unfolding of the P pili quaternary structure by stretching is reversible, not plastic2005Ingår i: EMBO Reports, ISSN 1469-221X, E-ISSN 1469-3178, Vol. 6, nr 1, s. 52-56Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    P pili are protein filaments expressed by uropathogenic Escherichia coli that mediate binding to glycolipids on epithelial cell surfaces, which is a prerequisite for bacterial infection. When a bacterium, attached to a cell surface, is exposed to external forces, the pili, which are composed of ∼103PapA protein subunits arranged in a helical conformation, can elongate by unfolding to a linear conformation. This property is considered important for the ability of a bacterium to withstand shear forces caused by urine flow. It has hitherto been assumed that this elongation is plastic, thus constituting a permanent conformational deformation. We demonstrate, using optical tweezers, that this is not the case; the unfolding of the helical structure to a linear conformation is fully reversible. It is surmised that this reversibility helps the bacteria regain close contact to the host cells after exposure to significant shear forces, which is believed to facilitate their colonization.

  • 16.
    Jass, Jana
    et al.
    Department of Microbiology and Immunology, The Lawson Health Research Institute, University of Western Ontario, London, Ontario, N6A 4V2, Canada.
    Schedin, Staffan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Olsson, J.
    Nilsson, U.
    Uhlin, Bernt Eric
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Physical properties of Escherichia coli P pili measured by optical tweezers2004Ingår i: Biophysical Journal, ISSN 0006-3495, E-ISSN 1542-0086, Biophysical Journal, Vol. 87, nr 6, s. 4271-4283Artikel i tidskrift (Refereegranskat)
  • 17.
    Klein, Markus
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Andersson, Magnus
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Dual-trap technique for reduction of low-frequency noise in force measuring optical tweezers2007Ingår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 46, nr 3, s. 405-412Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-resolution long-time force measurements by optical tweezers are often limited by low- frequency (1/f) noise. A dual-trap technique is presented that can reduce such noise in the force signal. It incorporates a second trap (a reference trap) that probes the noise in the system and it is based upon the assumption that the low-frequency parts of the noise from the two traps are correlated. A subtraction of the low-frequency signal from the reference trap from the signal from the force measuring trap will therefore yield a net signal that is significantly less influenced by noise. It is shown that this dual-trap technique can reduce the noise in the force signal up to 60% depending on detection bandwidth.

  • 18.
    Klein, Markus
    et al.
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Andersson, Magnus
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Fysik.
    Mechanical Noise Elimination in Optical Tweezers Force Measurements2007Ingår i: Applied Optics, Vol. 46, s. 405-412Artikel i tidskrift (Refereegranskat)
  • 19.
    Åberg, Veronica
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Fällman, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Axner, Ove
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Uhlin, Bernt Eric
    Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten).
    Hultgren, Scott J.
    Department of Molecular Microbiology, Washington University in St. Louis School of Medicine, St. Louis,USA.
    Almqvist, Fredrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Pilicides regulate pili expression in E. coli without affecting the functional properties of the pilus rod2007Ingår i: Molecular BioSystems, ISSN 1742-206X, Vol. 3, s. 214-218Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The infectious ability of uropathogenic Escherichia coli relies on adhesive fibers, termed pili or fimbriae, that are expressed on the bacterial surface. Pili are multi-protein structures that are formed via a highly preserved assembly and secretion system called the chaperone-usher pathway. We have earlier reported that small synthetic compounds, referred to as pilicides, disrupt both type 1 and P pilus biogenesis in E. coli. In this study, we show that the pilicides do not affect the structure, dynamics or function of the pilus rod. This was demonstrated by first suppressing the expression of P pili in E. coli by pilicide treatment and, next, measuring the biophysical properties of the pilus rod. The reduced abundance of pili was assessed with hemagglutination, atomic force microscopy and Western immunoblot analysis. The biodynamic properties of the pili fibers were determined by optical tweezers force measurements on individual pili and were found to be intact. The presented results establish a potential use of pilicides as chemical tools to study important biological processes e.g. adhesion, pilus biogenesis and the role of pili in infections and biofilm formation.

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