Dynamic Force Spectroscopy of E. coli P Pili
2006 (English)In: Biophysical Journal, ISSN 0006-3495, Vol. 91, no 7, 2717-2725 p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2006. Vol. 91, no 7, 2717-2725 p.
IdentifiersURN: urn:nbn:se:umu:diva-2745DOI: 10.1529/biophysj.106.087429OAI: oai:DiVA.org:umu-2745DiVA: diva2:141004