Role of 16S ribosomal RNA methylations in translation initiation in Escherichia coli
Role of 16S ribosomal RNA methylations in translation initiation in Escherichia coli
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DOI：
10.1038/emboj.2008.20
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发表时间：
2008-03-19
期刊：
影响因子：
11.4
通讯作者：
Varshney, Umesh
中科院分区：
文献类型：
--
作者：
Das, Gautam;Thotala, Dinesh Kumar;Varshney, Umesh
核糖体P-位点的翻译起始是启动子tRNAs(TRNA FMet)的特点。在它们的反密码子茎中存在三个连续的G-C碱基对(G29-C41、G30-C40和G31-C39)，这是启动子tRNAs在三个生命王国中高度保守的特征，这与它们与P-位点的优先结合有关。核糖体是如何利用这一特性的，目前还不清楚。使用遗传筛选，我们分离到一株大肠杆菌，它在折叠中携带G122D突变，这使得tRNA(FMet)能够启动包含一个、两个或所有三个G-C碱基对突变的tRNA(FMet)。该毒株严重缺乏蛋氨酸和S腺苷蛋氨酸，核糖核酸甲基化缺失。甲基转移酶基因的靶向突变揭示了rRNA修饰与核糖体选择启动子tRNA的基本过程之间的联系。
Translation initiation from the ribosomal P-site is the specialty of the initiator tRNAs ( tRNA fMet). Presence of the three consecutive G-C base pairs ( G29-C41, G30-C40 and G31-C39) in their anticodon stems, a highly conserved feature of the initiator tRNAs across the three kingdoms of life, has been implicated in their preferential binding to the P-site. How this feature is exploited by ribosomes has remained unclear. Using a genetic screen, we have isolated an Escherichia coli strain, carrying a G122D mutation in folD, which allows initiation with the tRNA(fMet) containing mutations in one, two or all the three G-C base pairs. The strain shows a severe deficiency of methionine and S-adenosylmethionine, and lacks nucleoside methylations in rRNA. Targeted mutations in the methyltransferase genes have revealed a connection between the rRNA modifications and the fundamental process of the initiator tRNA selection by the ribosome.