Hori Hiroyuki
Department of Materials Science and Biotechnology, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
Biomolecules. 2017 Feb 28;7(1):23. doi: 10.3390/biom7010023.
The existence of SpoU-TrmD (SPOUT) RNA methyltransferase superfamily was first predicted by bioinformatics. SpoU is the previous name of TrmH, which catalyzes the 2'-Omethylation of ribose of G18 in tRNA; TrmD catalyzes the formation of N1-methylguanosine at position 37 in tRNA. Although SpoU (TrmH) and TrmD were originally considered to be unrelated, the bioinformatics study suggested that they might share a common evolution origin and form a single superfamily. The common feature of SPOUT RNA methyltransferases is the formation of a deep trefoil knot in the catalytic domain. In the past decade, the SPOUT RNA methyltransferase superfamily has grown; furthermore, knowledge concerning the functions of their modified nucleosides in tRNA has also increased. Some enzymes are potential targets in the design of antibacterial drugs. In humans, defects in some genes may be related to carcinogenesis. In this review, recent findings on the tRNA methyltransferases with a SPOUT fold and their methylated nucleosides in tRNA, including classification of tRNA methyltransferases with a SPOUT fold; knot structures, domain arrangements, subunit structures and reaction mechanisms; tRNA recognition mechanisms, and functions of modified nucleosides synthesized by this superfamily, are summarized. Lastly, the future perspective for studies on tRNA modification enzymes are considered.
SpoU-TrmD（SPOUT）RNA甲基转移酶超家族的存在最早是通过生物信息学预测出来的。SpoU是TrmH的曾用名，TrmH催化tRNA中G18核糖的2'-O-甲基化；TrmD催化tRNA中第37位N1-甲基鸟苷的形成。尽管SpoU（TrmH）和TrmD最初被认为没有关联，但生物信息学研究表明它们可能有共同的进化起源并形成一个单一的超家族。SPOUT RNA甲基转移酶的共同特征是在催化结构域形成一个深三叶结。在过去十年中，SPOUT RNA甲基转移酶超家族不断发展；此外，关于其修饰的tRNA核苷功能的知识也有所增加。一些酶是抗菌药物设计中的潜在靶点。在人类中，某些基因的缺陷可能与癌症发生有关。在这篇综述中，总结了关于具有SPOUT折叠的tRNA甲基转移酶及其在tRNA中的甲基化核苷的最新发现，包括具有SPOUT折叠的tRNA甲基转移酶的分类；结结构、结构域排列、亚基结构和反应机制；tRNA识别机制，以及由该超家族合成的修饰核苷的功能。最后，考虑了tRNA修饰酶研究的未来前景。
