Evolving specificity of tRNA 3-methyl-cytidine-32 (m3C32) modification: a subset of tRNAsSer requires N6-isopentenylation of A37.
Evolving specificity of tRNA 3-methyl-cytidine-32 (m3C32) modification: a subset of tRNAsSer requires N6-isopentenylation of A37.
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DOI：
10.1261/rna.056259.116
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发表时间：
2016-09
期刊：
影响因子：
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通讯作者：
Maraia RJ
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文献类型：
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作者：
Arimbasseri AG;Iben J;Wei FY;Rijal K;Tomizawa K;Hafner M;Maraia RJ
反密码子环（ACL）核苷酸的转录后修饰影响tRNA结构、对核糖体的亲和力和解码活性，这些活性可以通过反密码子两侧核碱基之间的相互作用进行微调。最近发现的涉及位置32、34和37的ACL修饰回路被编码tRNA修饰酶的基因的人类疾病相关突变破坏。我们使用tRNA-HydroSeq （-HySeq）检测了酵母中仅存在于tRNAsSer和tRNAsThr的ACLs中的3methyl-cytidine-32 （m3C32）。在报道的酿酒酵母中，所有的m3C32都依赖于一个基因TRM140，与之相反，裂变酵母S. pombe的tRNAsSer和tRNAsThr的m3C32都依赖于两个相关基因TRM140 +和trm141+中的一个，它们的同源物在高等真核生物中被发现。有趣的是，哺乳动物和其他脊椎动物含有第三个同源物，并且在tRNAsArg上的32位和tRNAsSer可变臂上的C47:3位也含有m3C。更重要的是，通过检测S. pombe突变体缺乏其他修饰，我们发现含有反密码子碱基A36的三个tRNAsSer上的m3C32需要对A37进行n6 -异戊烯基修饰（i6A37）。这个新的C32-A37 ACL电路表明i6A37是这些trna上m3C32的先决条件或先决条件。对tRNA数据库的检查表明，这种电路可能比这里观察到的更广泛。结果强调了两个当代主题，tRNA修饰是相互关联的，并且具有相同反密码子身份的tRNA上的一些特定修饰是物种特异性的。
Post-transcriptional modifications of anticodon loop (ACL) nucleotides impact tRNA structure, affinity for the ribosome, and decoding activity, and these activities can be fine-tuned by interactions between nucleobases on either side of the anticodon. A recently discovered ACL modification circuit involving positions 32, 34, and 37 is disrupted by a human disease-associated mutation to the gene encoding a tRNA modification enzyme. We used tRNA-HydroSeq (-HySeq) to examine 3methyl-cytidine-32 (m3C32), which is found in yeast only in the ACLs of tRNAsSer and tRNAsThr. In contrast to that reported for Saccharomyces cerevisiae in which all m3C32 depends on a single gene, TRM140, the m3C32 of tRNAsSer and tRNAsThr of the fission yeast S. pombe, are each dependent on one of two related genes, trm140+ and trm141+, homologs of which are found in higher eukaryotes. Interestingly, mammals and other vertebrates contain a third homolog and also contain m3C at new sites, positions 32 on tRNAsArg and C47:3 in the variable arm of tRNAsSer. More significantly, by examining S. pombe mutants deficient for other modifications, we found that m3C32 on the three tRNAsSer that contain anticodon base A36, requires N6-isopentenyl modification of A37 (i6A37). This new C32–A37 ACL circuitry indicates that i6A37 is a pre- or corequisite for m3C32 on these tRNAs. Examination of the tRNA database suggests that such circuitry may be more expansive than observed here. The results emphasize two contemporary themes, that tRNA modifications are interconnected, and that some specific modifications on tRNAs of the same anticodon identity are species-specific.