Multimedia Gallery - A bacterium releases a protein (red) that disengages the clutch on its flagellum.

Illustration of the mechanism that stops the flagellum of a bacteria.

June 19, 2008

A bacterium releases a protein (red) that disengages the clutch on its flagellum.

Swimming helps bacteria look for food, escape bad conditions and disperse their genes. But when a bacterium needs to stop swimming, it produces a free-floating clutch (a protein shown in red), that sits down on a gear-like ring (orange), moving that gear away from the engine that spins the bacterium's flagellum. By disengaging the engine from the flagellum's other moving parts, the flagellum's tail is no longer driven to spin.

Credit: Zina Deretsky, National Science Foundation

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