The short form of the CheA protein restores kinase activity and chemotactic ability to kinase-deficient mutants.
Escherichia coli expresses two forms of the chemotaxis-associated CheA protein, CheAL and CheAS, as the result of translational initiation at two distinct, in-frame initiation sites in the gene cheA. The long form, CheAL, plays a crucial role in the chemotactic signal transduction mechanism by phosphorylating two other chemotaxis proteins: CheY and CheB. CheAL must first autophosphorylate at amino acid His-48 before transferring its phosphono group to these other signal transduction proteins. The short form, CheAS, lacks the N-terminal 97 amino acids of CheAL and, therefore, does not possess the site of autophosphorylation. Here we demonstrate that although it lacks the ability to autophosphorylate, CheAS can mediate phosphorylation of kinase-deficient variants of CheAL each of which retains a functional autophosphorylation site. This transphosphorylation enables these kinase-deficient CheAL variants to phosphorylate CheY. Because it mediates this activity, CheAS can restore to kinase-deficient E. coli cells the ability to tumble and, thus, to perform chemotaxis in swarm plate assays.
Wolfe
A J
AJ
Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL 60153.
Stewart
R C
RC
D001426:Bacterial Proteins; D002630:Chemotactic Factors / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D000071677:Histidine Kinase; D007700:Kinetics; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D009876:Operon; D010766:Phosphorylation; D016133:Polymerase Chain Reaction / Q000379:methods; D014176:Protein Biosynthesis; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D015183:Restriction Mapping; D013997:Time Factors
D001426:Bacterial Proteins; D002630:Chemotactic Factors; 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