Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10065, USA.
RNA. 2010 Feb;16(2):316-23. doi: 10.1261/rna.1926510. Epub 2009 Dec 9.
Hen1 is an RNA ribose 2'-O-methyltransferase that modifies the 3' terminal nucleoside of eukaryal small regulatory RNAs. Here, we report that Hen1 homologs are present in bacterial proteomes from eight different phyla. Bacterial Hen1 is encoded by the proximal ORF of a two-gene operon that also encodes polynucleotide kinase-phosphatase (Pnkp), an RNA repair enzyme. Purified recombinant Clostridium thermocellum Hen1 is a homodimer of a 465-amino acid polypeptide. CthHen1 catalyzes methyl transfer from AdoMet to the 3' terminal nucleoside of an RNA oligonucleotide, but is unreactive with a synonymous DNA oligonucleotide or an RNA with a single 3'-terminal deoxyribose sugar. CthHen1 is optimally active at alkaline pH and dependent on manganese. Activity is inhibited by AdoHcy and abolished by mutations D291A and D316A in the putative AdoMet-binding pocket. The C-terminal fragment, Hen1-(259-465), comprises an autonomous monomeric methyltransferase domain.
Hen1 是一种 RNA 核糖 2'-O-甲基转移酶，可修饰真核小分子调节 RNA 的 3'末端核苷。在这里，我们报告说 Hen1 同源物存在于来自八个不同门的细菌蛋白质组中。细菌 Hen1 由两个基因操纵子的近端 ORF 编码，该操纵子还编码多核苷酸激酶-磷酸酶（Pnkp），一种 RNA 修复酶。纯化的重组热纤梭菌 Hen1 是一个由 465 个氨基酸多肽组成的同源二聚体。CthHen1 催化 AdoMet 向 RNA 寡核苷酸 3'末端核苷的甲基转移，但与同义 DNA 寡核苷酸或带有单个 3'-末端脱氧核糖糖的 RNA 无反应。CthHen1 在碱性 pH 下活性最佳，依赖于锰。活性被 AdoHcy 抑制，并且在假定的 AdoMet 结合口袋中的突变 D291A 和 D316A 下被废除。C 末端片段 Hen1-(259-465) 包含自主的单体甲基转移酶结构域。
