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Publication Abstract from PubMed

The bacterial flagellar filament is a helical propeller constructed from 11 protofilaments of a single protein, flagellin. The filament switches between left- and right-handed supercoiled forms when bacteria switch their swimming mode between running and tumbling. Supercoiling is produced by two different packing interactions of flagellin called L and R. In switching from L to R, the intersubunit distance ( approximately 52 A) along the protofilament decreases by 0.8 A. Changes in the number of L and R protofilaments govern supercoiling of the filament. Here we report the 2.0 A resolution crystal structure of a Salmonella flagellin fragment of relative molecular mass 41,300. The crystal contains pairs of antiparallel straight protofilaments with the R-type repeat. By simulated extension of the protofilament model, we have identified possible switch regions responsible for the bi-stable mechanical switch that generates the 0.8 A difference in repeat distance.

Structure of the bacterial flagellar protofilament and implications for a switch for supercoiling.,Samatey FA, Imada K, Nagashima S, Vonderviszt F, Kumasaka T, Yamamoto M, Namba K Nature. 2001 Mar 15;410(6826):331-7. PMID:11268201^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.