Phosphorylation of an N-terminal regulatory domain activates the CheB methylesterase in bacterial chemotaxis.
Two types of reversible protein modification reactions have been identified in bacterial chemotaxis, methylation of membrane receptor-transducer proteins at glutamate side chains and phosphorylation of cytoplasmic signal transduction proteins at histidine and aspartate side chains. CheB is a bifunctional enzyme that is involved in both these modification processes. Its C-terminal domain is a methylesterase that catalyzes the hydrolysis of gamma-carboxyl glutamyl methyl esters in the cytoplasmic domain of chemoreceptor proteins. Its N-terminal domain is a phosphatase that catalyzes the hydrolysis of phospho-CheA, the central response regulator of bacterial chemotaxis. Phospho-CheB, produced as an intermediate in the phosphatase reaction, has dramatically increased methylesterase activity. The interplay between the methylesterase and phosphatase activities of CheB may provide a crucial link between adaptation and excitation in stimulus-response coupling.
Lupas
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Department of Molecular Biology, Princeton University, New Jersey 08544.
Stock
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D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D002633:Chemotaxis / Q000502:physiology*; D003001:Cloning, Molecular; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D008745:Methylation; D010766:Phosphorylation; D012486:Salmonella typhimurium / Q000201:enzymology*
D002265:Carboxylic Ester Hydrolases; C041144:chemotactic protein methylesterase