Dynamic restacking of Escherichia coli P-pili
2008 (English)In: European Biophysics Journal, ISSN 0175-7571, E-ISSN 1432-1017, Vol. 37, no 2, 111-120 p.Article in journal (Refereed) PublishedText
P-pili of uropathogenic Escherichia coli mediate the attachment to epithelial cells in the human urinary tract and kidney and therefore play an important role in infection. A better understanding of this mechanism could help to prevent bacteria from spreading but also provides interesting insights into molecular mechanics for future nanotech applications. The helical rod design of P-pili provides an efficient design to withstand hydrodynamic shear forces. The adhesive PapG unit at the distal end of the P-pilus forms a specific bond with the glycolipid Galabiose. This bond has a potential width Delta x = 0.7 (+/-) 0.15 nm and a dissociation rate K-Off = 8.0 center dot 10(-4) +/- 5.0 center dot 10(-4) s(-1). It with-stands a force of similar to 49 pN under physiological conditions. Additionally, we analyzed the behavior of unstacking and restacking of the P-pilus with dynamic force spectroscopy at velocities between 200 and 7,000 nm/s. Up to a critical extension of 66% of the totally stretched P-pilus, un/restacking was found to be fully reversible at velocities up to 200 nm/s. If the P-pilus is stretched beyond this critical extension a characteristic hysteresis appears upon restacking. This hysteresis originates from a nucleation process comparable to a first-order phase transition in an under-cooled liquid. Analysis of the measurement data suggests that 20 PapA monomers are involved in the formation of a nucleation kernel.
Place, publisher, year, edition, pages
New York: Springer-Verlag New York, 2008. Vol. 37, no 2, 111-120 p.
atomic force microscope (AFM), force spectroscopy, P-pilus, restacking, Escherichia Coli, PapA
IdentifiersURN: urn:nbn:se:umu:diva-117511DOI: 10.1007/s00249-007-0183-xISI: 000252276700001PubMedID: 17554533OAI: oai:DiVA.org:umu-117511DiVA: diva2:908300