The dynamics of protein phosphorylation in bacterial chemotaxis.
The chemotaxis signal transduction pathway allows bacteria to respond to changes in concentration of specific chemicals (ligands) by modulating their swimming behavior. The pathway includes ligand binding receptors, and the CheA, CheY, CheW, and CheZ proteins. We showed previously that phosphorylation of CheY is activated in reactions containing receptor, CheW, CheA, and CheY. Here we demonstrate that this activation signal results from accelerated autophosphorylation of the CheA kinase. Evidence for a second signal transmitted by a ligand-bound receptor, which corresponds to inhibition of CheA autophosphorylation, is also presented. We postulate that CheA can exist in three forms: a "closed" form in the absence of receptor and CheW; an "open" form that results from activation of CheA by receptor and CheW; and a "sequestered" form in reactions containing ligand-bound receptor and CheW. The system's dynamics depends on the relative distribution of CheA among these three forms at any time.
Borkovich
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Division of Biology, California Institute of Technology, Pasadena 91125.
Simon
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D001426:Bacterial Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002630:Chemotactic Factors / Q000378:metabolism; D002633:Chemotaxis; D004926:Escherichia coli / Q000378:metabolism / Q000502:physiology*; D029968:Escherichia coli Proteins; D000071677:Histidine Kinase; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism; D000072236:Methyl-Accepting Chemotaxis Proteins; D008954:Models, Biological; D010766:Phosphorylation; D015398:Signal Transduction
D001426:Bacterial Proteins; C489103:CheW protein, E coli; D002630:Chemotactic Factors; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; C000607606:cheY protein, E coli; C051236:CheW protein, Bacteria; D000071677:Histidine Kinase; C000607608:cheA protein, E coli