Signal transduction in bacteria: CheW forms a reversible complex with the protein kinase CheA.

AUTOR(ES)

Gegner, J A

RESUMO

An essential step in the signal transduction pathway of Escherichia coli is the control of the protein kinase activity of CheA by the chemotaxis receptor proteins. This control requires the participation of the CheW protein. Although the biochemical nature of the coupling between the receptors and the kinase is unknown, it is likely that CheW interacts with the receptors and with CheA. In this communication, we report direct measurement of a physical interaction between CheW and CheA. We utilized the equilibrium column chromatography method of Hummel and Dreyer to show that CheW and CheA exhibit reversible binding with the stoichiometry of two CheW monomers per CheA dimer. CheW was found to exist as monomers and CheA was found to exist as dimers by equilibrium analytical ultracentrifugation. The dissociation constant for the CheW-CheA interaction (in 160 mM KCl/5 mM MgCl2, pH 7.4 at 4 degrees C) was determined to be in the physiologically relevant range of 17 microM. No evidence for cooperativity in the association of CheW with CheA was found.

Documentos Relacionados

• Both CheA and CheW are required for reconstitution of chemotactic signaling in Escherichia coli.
• The carboxy-terminal portion of the CheA kinase mediates regulation of autophosphorylation by transducer and CheW.
• Genetic analysis of the catalytic domain of the chemotaxis-associated histidine kinase CheA.
• CheA, CheW, and CheY are required for chemotaxis to oxygen and sugars of the phosphotransferase system in Escherichia coli.
• Sensory transduction in Escherichia coli: regulation of the demethylation rate by the CheA protein.