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Proceedings Paper

Force measuring optical tweezers system for long time measurements of P pili stability
Author(s): Magnus Andersson; Erik Fällman; Bernt Eric Uhlin; Ove Axner
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Paper Abstract

A force-measuring optical tweezers instrumentation and long time measurements of the elongation and retraction of bacterial fimbriae from Uropathogenic E. coli (UPEC) under strain are presented. The instrumentation is presented in some detail. Special emphasis is given to measures taken to reduce the influence of noise and drifts in the system and from the surrounding, which makes long term force measurements possible. Individual P pili from UPEC bacteria were used as a biological model system for repetitive unfolding and refolding cycles of bacterial fimbriae under equilibrium conditions. P pili have evolved into a three-dimensional helix-like structure, the PapA rod, that can be successively and significantly elongated and/or unfolded when exposed to external forces. The instrumentation is used for characterization of the force-vs.-elongation response of the PapA rod of individual P pili, with emphasis on the long time stability of the forced unfolding and refolding of the helical structure of the PapA rod. The results show that the PapA rod is capable of withstanding extensive strain, leading to a complete unfolding of the helical structure, repetitive times during the life cycle of a bacterium without any noticeable alteration of the mechanical properties of the P pili. This function is believed to be importance for UPEC bacteria in vivo since it provides a close contact to a host cell (which is an initial step of invasion) despite urine cleaning attempts.

Paper Details

Date Published: 21 February 2006
PDF: 10 pages
Proc. SPIE 6088, Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues IV, 608810 (21 February 2006); doi: 10.1117/12.642266
Show Author Affiliations
Magnus Andersson, Umeå Univ. (Sweden)
Erik Fällman, Umeå Univ. (Sweden)
Bernt Eric Uhlin, Umeå Univ. (Sweden)
Ove Axner, Umeå Univ. (Sweden)

Published in SPIE Proceedings Vol. 6088:
Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues IV
Daniel L. Farkas; Dan V. Nicolau; Robert C. Leif, Editor(s)

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