Department of Systems Immunology, College of Biomedical Science, Kangwon National University, Chuncheon 200-701, Republic of Korea.
Department of Systems Immunology, College of Biomedical Science, Kangwon National University, Chuncheon 200-701, Republic of Korea; Institute of Bioscience and Biotechnology, Kangwon National University, Chuncheon 200-701, Republic of Korea.
Biochem Biophys Res Commun. 2014 Apr 18;446(4):921-6. doi: 10.1016/j.bbrc.2014.03.026. Epub 2014 Mar 14.
S-adenosyl-L-methionine (SAM)-dependent methyltransferases (MTases) methylate diverse biological molecules using a SAM cofactor. The ytqB gene of Bacillus subtilis encodes a putative MTase and its biological function has never been characterized. To reveal the structural features and the cofactor binding mode of YtqB, we have determined the crystal structures of YtqB alone and in complex with its cofactor, SAM, at 1.9 Å and 2.2 Å resolutions, respectively. YtqB folds into a β-sheet sandwiched by two α-helical layers, and assembles into a dimeric form. Each YtqB monomer contains one SAM binding site, which shapes SAM into a slightly curved conformation and exposes the reactive methyl group of SAM potentially to a substrate. Our comparative structural analysis of YtqB and its homologues indicates that YtqB is a SAM-dependent class I MTase, and provides insights into the substrate binding site of YtqB.
S-腺苷甲硫氨酸（SAM）依赖性甲基转移酶（MTases）使用 SAM 辅因子甲基化多种生物分子。枯草芽孢杆菌的 ytqB 基因编码一种假定的 MTase，但其生物学功能尚未得到表征。为了揭示 YtqB 的结构特征和辅因子结合模式，我们分别测定了 YtqB 单体及其与辅因子 SAM 复合物的晶体结构，分辨率分别为 1.9 Å 和 2.2 Å。YtqB 折叠成由两个α-螺旋层夹在中间的β-折叠，组装成二聚体形式。每个 YtqB 单体包含一个 SAM 结合位点，该位点将 SAM 塑造成略微弯曲的构象，并使 SAM 的反应性甲基基团潜在地暴露于底物。我们对 YtqB 及其同源物的比较结构分析表明，YtqB 是一种 SAM 依赖性的 I 类 MTase，并为 YtqB 的底物结合位点提供了深入了解。
