title: Mutational analysis of the P1 phosphorylation domain in Escherichia coli CheA, the signaling kinase for chemotaxis.
abstract: The histidine autokinase CheA functions as the central processing unit in the Escherichia coli chemotaxis signaling machinery. CheA receives autophosphorylation control inputs from chemoreceptors and in turn regulates the flux of signaling phosphates to the CheY and CheB response regulator proteins. Phospho-CheY changes the direction of flagellar rotation; phospho-CheB covalently modifies receptor molecules during sensory adaptation. The CheA phosphorylation site, His-48, lies in the N-terminal P1 domain, which must engage the CheA ATP-binding domain, P4, to initiate an autophosphorylation reaction cycle. The docking determinants for the P1-P4 interaction have not been experimentally identified. We devised mutant screens to isolate P1 domains with impaired autophosphorylation or phosphotransfer activities. One set of P1 mutants identified amino acid replacements at surface-exposed residues distal to His-48. These lesions reduced the rate of P1 transphosphorylation by P4. However, once phosphorylated, the mutant P1 domains transferred phosphate to CheY at the wild-type rate. Thus, these P1 mutants appear to define interaction determinants for P1-P4 docking during the CheA autophosphorylation reaction.
authors.affiliation: Department of Biology, University of Utah, Salt Lake City, Utah, USA.
authors.forename: So-ichiro
authors.initials: S
authors.lastname: Nishiyama
authors.forename: Andrés
authors.initials: A
authors.lastname: Garzón
authors.forename: John S
authors.initials: JS
authors.lastname: Parkinson
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D002633:Chemotaxis; D004252:DNA Mutational Analysis; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins; D000071677:Histidine Kinase; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D008954:Models, Biological; D010766:Phosphorylation; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000235:genetics; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; C000607606:cheY protein, E coli; D011494:Protein Kinases; D000071677:Histidine Kinase; C000607608:cheA protein, E coli