Abstract
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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism*
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Chemotaxis*
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Escherichia coli / genetics
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Escherichia coli / metabolism
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Escherichia coli / physiology
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Escherichia coli Proteins
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Flagella / metabolism
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Flagella / physiology
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Green Fluorescent Proteins / genetics
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Green Fluorescent Proteins / metabolism*
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Immunoblotting
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Intracellular Space / metabolism
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Membrane Proteins / genetics
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Membrane Proteins / metabolism
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Methyl-Accepting Chemotaxis Proteins
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Microscopy, Fluorescence / methods*
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Molecular Dynamics Simulation
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Molecular Motor Proteins / metabolism
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Phosphorylation
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Protein Binding
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Rotation
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Signal Transduction*
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Time-Lapse Imaging
Substances
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Bacterial Proteins
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Escherichia coli Proteins
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Membrane Proteins
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Methyl-Accepting Chemotaxis Proteins
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Molecular Motor Proteins
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cheY protein, E coli
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Green Fluorescent Proteins