Microbiology

Feeling Dehydrated

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Science  20 May 2005:
Vol. 308, Issue 5725, pp. 1089
DOI: 10.1126/science.308.5725.1089a

Bacteria monitor their environment and change their behavior to exploit that environment most effectively. Wang et al. have discovered an unanticipated player that bacteria use to sense environmental wetness: the bacterial flagellum. One key ingredient for continued growth is a source of water; at a hydrated surface, bacteria form large colonies that swarm across the surface via flagella-driven motility. Mutants in the bacterial chemotaxis signaling pathway exhibit fewer and shorter flagella when grown on a surface and are less hydrated than wildtype cells. It seems that the flagella sense external wetness, and when external hydration is limiting, the flagella inhibit their own growth by blocking the secretion of flagellin subunits and the export of the transcriptional inhibitor FlgM, thereby switching off the synthesis of further flagellum components. The specialized secretion systems responsible for the export and assembly of flagella and for the secretion of bacterial virulence factors are jointly regulated by this sensing system. — SMH

EMBO J. 10.1038/sj.emboj.7600668 (2005).

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