Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
Department of Medical Microbiology and Immunology, and Program in Bioinformatics, The University of Toledo College of Medicine and Life Sciences, Toledo, OH 43614, USA.
Nucleic Acids Res. 2020 Oct 9;48(18):10034-10044. doi: 10.1093/nar/gkaa446.
S-adenosyl-l-methionine dependent methyltransferases catalyze methyl transfers onto a wide variety of target molecules, including DNA and RNA. We discuss a family of methyltransferases, those that act on the amino groups of adenine or cytosine in DNA, have conserved motifs in a particular order in their amino acid sequence, and are referred to as class beta MTases. Members of this class include M.EcoGII and M.EcoP15I from Escherichia coli, Caulobacter crescentus cell cycle-regulated DNA methyltransferase (CcrM), the MTA1-MTA9 complex from the ciliate Oxytricha, and the mammalian MettL3-MettL14 complex. These methyltransferases all generate N6-methyladenine in DNA, with some members having activity on single-stranded DNA as well as RNA. The beta class of methyltransferases has a unique multimeric feature, forming either homo- or hetero-dimers, allowing the enzyme to use division of labor between two subunits in terms of substrate recognition and methylation. We suggest that M.EcoGII may represent an ancestral form of these enzymes, as its activity is independent of the nucleic acid type (RNA or DNA), its strandedness (single or double), and its sequence (aside from the target adenine).
S-腺苷甲硫氨酸依赖性甲基转移酶催化将甲基转移到各种靶分子上，包括 DNA 和 RNA。我们讨论了一类甲基转移酶，它们作用于 DNA 中腺嘌呤或胞嘧啶的氨基，在其氨基酸序列中以特定的顺序具有保守的基序，并被称为β类 MTases。该类的成员包括大肠杆菌中的 M.EcoGII 和 M.EcoP15I、新月柄杆菌细胞周期调控的 DNA 甲基转移酶 (CcrM)、纤毛虫 Oxytricha 的 MTA1-MTA9 复合物，以及哺乳动物的 MettL3-MettL14 复合物。这些甲基转移酶都在 DNA 中生成 N6-甲基腺嘌呤，其中一些成员对单链 DNA 和 RNA 都有活性。β类甲基转移酶具有独特的多聚体特征，形成同型或异型二聚体，使酶能够在底物识别和甲基化方面利用两个亚基之间的分工。我们认为 M.EcoGII 可能代表这些酶的原始形式，因为其活性不依赖于核酸类型（RNA 或 DNA）、链的极性（单链或双链）以及序列（除了靶腺嘌呤之外）。
Zotero 插件
