Translational adaptation to heat stress is mediated by RNA 5-methylcytosine in Caenorhabditis elegans.
Translational adaptation to heat stress is mediated by RNA 5-methylcytosine in Caenorhabditis elegans.
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DOI：
10.15252/embj.2020105496
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发表时间：
2021-03-15
期刊：
影响因子：
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通讯作者：
Miska EA
中科院分区：
文献类型：
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作者：
Navarro IC;Tuorto F;Jordan D;Legrand C;Price J;Braukmann F;Hendrick AG;Akay A;Kotter A;Helm M;Lyko F;Miska EA
胞嘧啶碳- 5甲基化（m5C）是在所有生物王国中发现的RNA转录后核苷酸修饰。虽然已经对单个m5C‐甲基转移酶进行了研究，但胞嘧啶‐5甲基组对发育、体内平衡和应激的影响尚不清楚。在这里，我们使用秀丽隐杆线虫，产生了第一个在RNA中缺乏m5C的生物体，证明这种修饰是不必要的。使用这种遗传工具，我们确定了体内RNome中m5C位点的定位和酶的特异性。我们发现NSUN‐4在秀丽隐杆线虫线粒体中作为双重rRNA和tRNA甲基转移酶。与亮氨酸和脯氨酸是最常甲基化的tRNA同受体一致，m5C的缺失会影响这两种氨基酸的一些三联体的解码，导致翻译效率降低。在热应激时，m5C的丢失导致核糖体在UUG三联体（唯一由m5C34修饰的tRNA翻译的密码子）上停滞。这导致富含UUG转录本的翻译效率降低和生育能力受损，表明m5C tRNA摆动甲基化在高温适应中的作用。对缺乏m5C RNA修饰的蠕虫突变体的分析揭示了它们对高效的Leu/Pro密码子翻译的贡献，以及在更高温度下支持育性的Leu - UUG解码的需求。
Methylation of carbon‐5 of cytosines (m5C) is a post‐transcriptional nucleotide modification of RNA found in all kingdoms of life. While individual m5C‐methyltransferases have been studied, the impact of the global cytosine‐5 methylome on development, homeostasis and stress remains unknown. Here, using Caenorhabditis elegans, we generated the first organism devoid of m5C in RNA, demonstrating that this modification is non‐essential. Using this genetic tool, we determine the localisation and enzymatic specificity of m5C sites in the RNome in vivo. We find that NSUN‐4 acts as a dual rRNA and tRNA methyltransferase in C. elegans mitochondria. In agreement with leucine and proline being the most frequently methylated tRNA isoacceptors, loss of m5C impacts the decoding of some triplets of these two amino acids, leading to reduced translation efficiency. Upon heat stress, m5C loss leads to ribosome stalling at UUG triplets, the only codon translated by an m5C34‐modified tRNA. This leads to reduced translation efficiency of UUG‐rich transcripts and impaired fertility, suggesting a role of m5C tRNA wobble methylation in the adaptation to higher temperatures. Analysis of worm mutants devoid of m5C RNA modifications uncovers their contribution to efficient Leu/Pro codon translation, and requirement for fertility‐supporting Leu‐UUG decoding at higher temperatures.