The c-di-GMP binding protein YcgR controls flagellar motor direction and speed to affect chemotaxis by a "backstop brake" mechanism.
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Paul K, Nieto V, Carlquist WC, Blair DF, Harshey RM
The c-di-GMP binding protein YcgR controls flagellar motor direction and speed to affect chemotaxis by a "backstop brake" mechanism.
Mol Cell. 2010 Apr 9;38(1):128-39. doi: 10.1016/j.molcel.2010.03.001. Epub 2010 Mar 25.
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- 20346719 [ View in PubMed]
- Abstract
We describe a mechanism of flagellar motor control by the bacterial signaling molecule c-di-GMP, which regulates several cellular behaviors. E. coli and Salmonella have multiple c-di-GMP cyclases and phosphodiesterases, yet absence of a specific phosphodiesterase YhjH impairs motility in both bacteria. yhjH mutants have elevated c-di-GMP levels and require YcgR, a c-di-GMP-binding protein, for motility inhibition. We demonstrate that YcgR interacts with the flagellar switch-complex proteins FliG and FliM, most strongly in the presence of c-di-GMP. This interaction reduces the efficiency of torque generation and induces CCW motor bias. We present a "backstop brake" model showing how both effects can result from disrupting the organization of the FliG C-terminal domain, which interacts with the stator protein MotA to generate torque. Inhibition of motility and chemotaxis may represent a strategy to prepare for sedentary existence by disfavoring migration away from a substrate on which a biofilm is to be formed.