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The unfolding of the P pili quaternary structure by stretching is reversible, not plastic
Author(s) -
Fällman Erik,
Schedin Staffan,
Jass Jana,
Uhlin BerntEric,
Axner Ove
Publication year - 2005
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/sj.embor.7400310
Subject(s) - pilus , biophysics , optical tweezers , chemistry , escherichia coli , protein quaternary structure , elongation , bacteria , crystallography , protein structure , biology , biochemistry , materials science , protein subunit , physics , optics , gene , genetics , ultimate tensile strength , metallurgy
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 ∼10 3 PapA 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.