title: Chemotaxis receptor recognition by protein methyltransferase CheR.
abstract: Signal transduction processes commonly involve reversible covalent modifications of receptors. Bacterial chemotaxis receptors are reversibly methylated at specific glutamate residues within coiled-coil regions of their cytoplasmic domains. Methylation is catalyzed by an S-adenosylmethionine-dependent protein methyltransferase, CheR, that binds to a specific sequence at the C-termini of some chemotaxis receptors. From this tethering point, CheR methylates neighboring receptor molecules. We report the crystal structure, determined to 2.2 A resolution, of a complex of the Salmonella typhimurium methyltransferase CheR bound to the methylation reaction product, S-adenosylhomocysteine (AdoHcy), and the C-terminal pentapeptide of the aspartate receptor, Tar. The structure indicates the basis for the specificity of interaction between the chemoreceptors and CheR and identifies a specific receptor binding motif incorporated in the CheR methyltransferase domain.
authors.affiliation: Howard Hughes Medical Institute, Center for Advanced Biotechnology and Medicine, and Department of Biochemistry, University of Medicine and Dentistry of New Jersey, Piscataway 08854-5638, USA.
authors.forename: S
authors.initials: S
authors.lastname: Djordjevic
authors.forename: A M
authors.initials: AM
authors.lastname: Stock
mesh_terms: D000595:Amino Acid Sequence; D001224:Aspartic Acid / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites; D002628:Chemoreceptor Cells; D002633:Chemotaxis; D018360:Crystallography, X-Ray; D029968:Escherichia coli Proteins; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D008780:Methyltransferases / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry; D017459:Receptors, Amino Acid / Q000737:chemistry; D011956:Receptors, Cell Surface; D012435:S-Adenosylhomocysteine / Q000378:metabolism; D012486:Salmonella typhimurium
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D009842:Oligopeptides; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface; C057331:Tar protein, E coli; C031959:aspartic acid receptor; D001224:Aspartic Acid; D012435:S-Adenosylhomocysteine; D008780:Methyltransferases; C038706:chemotaxis methyltransferase