Yan Qiaoling, Shaw Neil, Qian Lanfang, Jiang Dunquan
College of Life Science, Nankai University, Weijin Road, Nankai District, Tianjin City 300071, People's Republic of China.
Acta Crystallogr F Struct Biol Commun. 2017 Jun 1;73(Pt 6):315-320. doi: 10.1107/S2053230X17006057. Epub 2017 May 11.
Rv1220c from Mycobacterium tuberculosis is annotated as an O-methyltransferase (MtbOMT). Currently, no structural information is available for this protein. Here, the crystal structure of MtbOMT refined to 2.0 Å resolution is described. The structure reveals the presence of a methyltransferase fold and shows clear electron density for one molecule of S-adenosylmethionine (SAM), which was apparently bound by the protein during its production in Escherichia coli. Although the overall structure of MtbOMT resembles the structures of O-methyltransferases from Cornybacterium glutamicum, Coxiella burnetti and Alfa alfa, differences are observed in the residues that make up the active site. Notably, substitution of Asp by His164 seems to abrogate metal binding by MtbOMT. A putative catalytic His-Asp pair located in the vicinity of SAM is absolutely conserved in MtbOMT homologues from all species of Mycobacterium, suggesting a conserved function for this protein.
来自结核分枝杆菌的Rv1220c被注释为O-甲基转移酶（MtbOMT）。目前，尚无该蛋白的结构信息。在此，描述了分辨率为2.0 Å的MtbOMT晶体结构。该结构揭示了存在甲基转移酶折叠，并显示出一分子S-腺苷甲硫氨酸（SAM）的清晰电子密度，SAM显然是在其于大肠杆菌中产生期间被该蛋白结合的。尽管MtbOMT的整体结构类似于谷氨酸棒杆菌、伯氏考克斯氏体和紫花苜蓿的O-甲基转移酶的结构，但在构成活性位点的残基中观察到了差异。值得注意的是，His164取代Asp似乎消除了MtbOMT的金属结合。位于SAM附近的一个假定的催化His-Asp对在所有分枝杆菌物种的MtbOMT同源物中绝对保守，表明该蛋白具有保守功能。
