Structural Biology

A hook to understand motility

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Science  08 Nov 2019:
Vol. 366, Issue 6466, pp. 703-704
DOI: 10.1126/science.366.6466.703-e

Bacterial flagella provide the motility required for pathogenicity and biofilm formation. Flagella comprise a motor anchored in the cell membrane, a filament propeller, and a hook region that transmits torque between the motor and the filament. Shibata et al. resolved the complete structure of the hook from Salmonella enterica by cryo–electron microscopy at 2.9-angstrom resolution without imposing helical symmetry. The single protein forms a supercoiled tubular helix composed of 11 protofilaments. Although the hook is built from a single protein, subunits in each protofilament have a slightly different conformation because angles between the three domains are gradually adjusted by interdomain interactions. The conformational tweaks form a curved hook that can rotate by dynamic switching between states. A companion piece by Egelman further discusses the work.

Nat. Struct. Mol. Biol. 26, 941, 848 (2019).

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