This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.105.074674v1 90/5/1521    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Andersson, M. Articles by Axner, O. Search for Related Content PubMed PubMed Citation Articles by Andersson, M. Articles by Axner, O.

A Sticky Chain Model of the Elongation and Unfolding of Escherichia coli P Pili under Stress

Magnus Andersson ^*, Erik Fällman ^*, Bernt Eric Uhlin  and Ove Axner ^*

^* Department of Physics and Department of Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden

Correspondence: Address reprint requests to Ove Axner, Dept. of Physics, Umeå University, Se-901 87 Umeå, Sweden. E-mail: ove.axner{at}physics.umu.se.

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.

This article has been cited by other articles:

				M. Andersson, B. E. Uhlin, and E. Fallman The Biomechanical Properties of E. coli Pili for Urinary Tract Attachment Reflect the Host Environment Biophys. J., November 1, 2007; 93(9): 3008 - 3014. [Abstract] [Full Text] [PDF]

				E. Miller, T. Garcia, S. Hultgren, and A. F. Oberhauser The Mechanical Properties of E. coli Type 1 Pili Measured by Atomic Force Microscopy Techniques Biophys. J., November 15, 2006; 91(10): 3848 - 3856. [Abstract] [Full Text] [PDF]

				M. Andersson, E. Fallman, B. E. Uhlin, and O. Axner Dynamic Force Spectroscopy of E. coli P Pili Biophys. J., October 1, 2006; 91(7): 2717 - 2725. [Abstract] [Full Text] [PDF]