Chemotactic methylation and behavior in Bacillus subtilis: role of two unique proteins, CheC and CheD.
We characterized mutants in two novel genes of Bacillus subtilis, cheC and cheD. Mutants in CheC had a high smooth swimming bias and exhibited poor adaptation to positive stimuli. Analysis of tethered cells revealed two distinct subpopulations which differ in their prestimulus bias and extent of adaptation. The receptors, the methyl-accepting chemotaxis proteins (MCPs), of this mutant strain were overmethylated, as a result of an increase in CheR activity. We speculate that CheC helps to control tumbling frequency by regulating CheR, perhaps by a feedback mechanism through the MCPs. In contrast, a cheD mutant exhibited very tumbly behavior, and many of the MCPs were unmethylated. It seems that some B. subtilis MCPs require the presence of CheD for CheR to methylate them, a unique feature of B. subtilis chemotaxis. It is hypothesized that CheD is part of a complex that facilitates methylation of some of the MCPs, and dissociation of CheD from this complex affects CheA activity and may help bring about adaptation.
Rosario
M M
MM
Department of Biochemistry, College of Medicine, University of Illinois, Urbana 61801.
Kirby
J R
JR
Bochar
D A
DA
Ordal
G W
GW
D001412:Bacillus subtilis / Q000166:cytology*; D001426:Bacterial Proteins; D002633:Chemotaxis / Q000235:genetics; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D005816:Genetic Complementation Test; D000071677:Histidine Kinase; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D000072236:Methyl-Accepting Chemotaxis Proteins; D008745:Methylation; D008780:Methyltransferases / Q000378:metabolism; D009154:Mutation
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; C000607604:tsr protein, E coli; D008780:Methyltransferases; C038706:chemotaxis methyltransferase; D000071677:Histidine Kinase; C000607608:cheA protein, E coli