Research ArticleMicrobiology

Direct Imaging of Intracellular Signaling Components That Regulate Bacterial Chemotaxis

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Sci. Signal.  01 Apr 2014:
Vol. 7, Issue 319, pp. ra32
DOI: 10.1126/scisignal.2004963

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The bacterial chemotaxis system regulates the rotational direction of flagellar motors through an intracellular signaling molecule, the phosphorylated form of CheY (CheY-P). The binding of CheY-P to a motor is believed to switch the motor’s rotational direction from counterclockwise to clockwise. We demonstrated that the rotational switch of a motor was directly regulated by the binding and dissociation of CheY-P by simultaneously visualizing CheY tagged with green fluorescent protein and the rotational switching of a motor in live cells. The binding of 13 ± 7 CheY-P molecules was sufficient to induce clockwise rotation, and CheY-P molecules bound to and dissociated from a motor within ~100 ms during switching. Thus, we have directly measured the regulation of the output from a signal transduction pathway by intracellular signaling proteins.

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