Signaling activity of bacterial chemotaxis transmembrane receptors is modulated by reversible covalent modification of specific receptor glutamate residues. The level of receptor methylation results from the activities of a specific S-adenosylmethion ...
Signaling activity of bacterial chemotaxis transmembrane receptors is modulated by reversible covalent modification of specific receptor glutamate residues. The level of receptor methylation results from the activities of a specific S-adenosylmethionine-dependent methyltransferase, CheR, and the CheB methylesterase, which catalyzes hydrolysis of receptor glutamine or methylglutamate side-chains to glutamic acid. The CheB methylesterase belongs to a large family of response regulator proteins in which N-terminal regulatory domains control the activities of C-terminal effector domains. The crystal structure of the catalytic domain of the Salmonella typhimurium CheB methylesterase has been determined at 1.75 A resolution. The domain has a modified, doubly wound alpha/beta fold in which one of the helices is replaced by an anti-parallel beta-hairpin. Previous biochemical and mutagenesis data, suggest that the methylester hydrolysis catalyzed by CheB proceeds through a mechanism involving a serine nucleophile. The methylesterase active site is tentatively identified as a cleft at the C-terminal edge of the beta-sheet containing residues Ser164, His190 and Asp286. The three-dimensional fold, and the arrangement of residues within the catalytic triad distinguishes the CheB methylesterase from any previously described serine protease or serine hydrolase.
Related Citations:
Purification, Crystallization, and Preliminary X-Ray Diffraction Analyses of the Bacterial Chemotaxis Receptor Modifying Enzymes West, A.H.,Djordjevic, S.,Martinez-Hackert, E.,Stock, A.M. () TO BE PUBLISHED --: --
Evidence that the Methylesterase of Bacterial Chemotaxis May be a Serine Hydrolase Krueger, J.K.,Stock, J.,Schutt, C.E. (1992) Biochim.Biophys.Acta 1119: 322
Bacterial Chemotaxis and the Molecular Logic of Intracellular Signal Transduction Networks Stock, J.B.,Lukat, G.S.,Stock, A.M. (1991) Annu.Rev.Biophys.Biophys.Chem. 20: 109
Multiple Forms of the Cheb Methylesterase in Bacterial Chemosensing Simms, S.A.,Keane, M.G.,Stock, J. (1985) J.Biol.Chem. 260: 10161
Organizational Affiliation:
Department of Biochemistry, University of Medicine and Dentistry, New Jersey-Robert Wood Johnson Medical School,Piscataway USA.
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