Djordjevic S, Stock A M
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.
Nat Struct Biol. 1998 Jun;5(6):446-50. doi: 10.1038/nsb0698-446.
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.
信号转导过程通常涉及受体的可逆共价修饰。细菌趋化性受体在其细胞质结构域的卷曲螺旋区域内的特定谷氨酸残基处发生可逆甲基化。甲基化由一种依赖S-腺苷甲硫氨酸的蛋白质甲基转移酶CheR催化，该酶与某些趋化性受体C末端的特定序列结合。从这个附着点开始，CheR对相邻的受体分子进行甲基化。我们报告了鼠伤寒沙门氏菌甲基转移酶CheR与甲基化反应产物S-腺苷高半胱氨酸（AdoHcy）以及天冬氨酸受体Tar的C末端五肽形成的复合物的晶体结构，分辨率为2.2埃。该结构揭示了化学感受器与CheR之间相互作用特异性的基础，并确定了CheR甲基转移酶结构域中包含的一个特定受体结合基序。
