Intermolecular complementation of the kinase activity of CheA.
CheA is a dimeric autophosphorylating protein kinase that plays a critical role in the signal transduction network controlling chemotaxis in Escherichia coli. The autophosphorylation reaction was analysed using mutant proteins defective in kinase and regulatory functions. Proteins in which the site of autophosphorylation was mutated (CheA48HQ) or missing (CheAs) were found to phosphorylate the kinase-defective mutant, CheA470GK. The kinetics of this reaction support the hypothesis that autophosphorylation is the result of trans-phosphorylation within a dimer. The carboxy-terminal portion of CheA was previously shown to be dispensable for autophosphorylation, but required for regulation in response to environmental signals transmitted through a transducer and CheW. Mixing of CheA48HQ or CheA470GK with a truncated protein lacking this regulatory domain demonstrated that regulated autophosphorylation requires the presence of both carboxy-terminal portions in a CheA dimer. These results indicate that the dimeric form of CheA plays an integral role in signal transduction in bacterial chemotaxis.
Swanson
R V
RV
Division of Biology, California Institute of Technology, Pasadena 91125.
Bourret
R B
RB
Simon
M I
MI
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002633:Chemotaxis; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D005816:Genetic Complementation Test; D006639:Histidine / Q000378:metabolism; D000071677:Histidine Kinase; D007700:Kinetics; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D000072236:Methyl-Accepting Chemotaxis Proteins; D010766:Phosphorylation; D011487:Protein Conformation; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D015398:Signal Transduction
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D006639:Histidine; D011494:Protein Kinases; D000071677:Histidine Kinase; C000607608:cheA protein, E coli