title: Phosphorylation-dependent binding of the chemotaxis signal molecule CheY to its phosphatase, CheZ.
abstract: Bacterial chemotaxis is accomplished by regulating the direction of flagellar rotation. The primary target of the control appears to be CheY, a diffusible clockwise-signal molecule which interacts with the switch at the base of the flagellar motor and causes clockwise rotation. The regulatory mechanism appears to be phosphorylation/dephosphorylation of CheY. Here we demonstrate that CheZ, which accelerates the dephosphorylation of CheY, binds to CheY (immobilized on CNBr-activated Sepharose beads), that the binding to phosphorylated CheY is higher by over 2 orders of magnitude than the binding to nonphosphorylated CheY, and that the binding to both the phosphorylated and nonphosphorylated forms of CheY is significantly higher in the presence of Mg2+. We also show that the mutant proteins CheY13DK, CheY57DE, and CheY109KR bind CheZ to the same extent as wild-type CheY. The extent of the binding of these mutant proteins was not, however, increased in the presence of acetyl phosphate, the phosphorylating agent. The results indicate that neither a conformation which has a clockwise-causing activity in vivo nor phosphorylation is sufficient, alone, for maximal binding of CheZ to CheY and that Mg2+ is required for the binding of these proteins as well as for the phosphorylation and dephosphorylation of CheY.
authors.affiliation: Department of Membrane Research and Biophysics, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Y
authors.initials: Y
authors.lastname: Blat
authors.forename: M
authors.initials: M
authors.lastname: Eisenbach
mesh_terms: D001426:Bacterial Proteins; D001665:Binding Sites; D002633:Chemotaxis; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics; D029968:Escherichia coli Proteins; D008274:Magnesium / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D009154:Mutation; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; C000607606:cheY protein, E coli; D010744:Phosphoric Monoester Hydrolases; D008274:Magnesium