Impact of intron removal from tRNA genes on Saccharomyces cerevisiae
Impact of intron removal from tRNA genes on Saccharomyces cerevisiae
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DOI：
10.1093/nar/gkz270
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发表时间：
2019-06-20
影响因子：
14.9
通讯作者：
Yoshihisa, Tohru
中科院分区：
文献类型：
--
作者：
Hayashi, Sachiko;Mori, Shunsuke;Yoshihisa, Tohru
在真核生物和古细菌中，tRNA 基因经常含有内含子，这些内含子在成熟过程中被去除。然而，tRNA 内含子的生物学作用仍然难以捉摸。在这里，我们构建了一套完整的酿酒酵母菌株，其中内含子从编码 10 种不同 tRNA 物种的所有同义基因中删除。所有无内含子菌株均能存活，但 tRNA(GAA)(Phe) 和 tRNA(GUA)(Tyr) 无内含子菌株在呼吸条件下表现出生长缓慢、冷敏感性和生长缺陷，表明某些 tRNA 内含子的生理重要性。 Northern 分析表明，从编码三个 tRNA 的基因中去除内含子会减少相应成熟 tRNA 的数量，但不会影响氨酰化。出乎意料的是，tRNA(CAA)(Leu)无内含子菌株表现出5.8S rRNA水平降低和核仁形态异常。由于假尿苷 (Psi) 以内含子依赖性方式出现在 tRNA(UAU)(Ile) 反密码子的第 34 位，因此无内含子菌株中的 tRNA(UAU)(Ile) 丢失了 Psi 34。然而，在 tRNA(UAU)(Ile) 群体的一部分中，第 34 位被转化为 5-氨基甲酰甲基尿苷 (ncm(5)U)，这可能会降低解码保真度。总之，我们的结果表明，虽然内含子对于细胞活力来说是可有可无的，但一些内含子具有不同的作用，例如确保在各种条件下适当的生长以及控制适当的反密码子修饰以与密码子准确配对。
In eukaryotes and archaea, tRNA genes frequently contain introns, which are removed during maturation. However, biological roles of tRNA introns remain elusive. Here, we constructed a complete set of Saccharomyces cerevisiae strains in which the introns were removed from all the synonymous genes encoding 10 different tRNA species. All the intronless strains were viable, but the tRNA(GAA)(Phe) and tRNA(GUA)(Tyr) intronless strains displayed slow growth, cold sensitivity and defective growth under respiratory conditions, indicating physiological importance of certain tRNA introns. Northern analyses revealed that removal of the introns from genes encoding three tRNAs reduced the amounts of the corresponding mature tRNAs, while it did not affect aminoacylation. Unexpectedly, the tRNA(CAA)(Leu) intronless strain showed reduced 5.8S rRNA levels and abnormal nucleolar morphology. Because pseudouridine (Psi) occurs at position 34 of the tRNA(UAU)(Ile) anticodon in an intron-dependent manner, tRNA(UAU)(Ile) in the intronless strain lost Psi 34. However, in a portion of tRNA(UAU)(Ile) population, position 34 was converted into 5-carbamoylmethyluridine (ncm(5)U), which could reduce decoding fidelity. In summary, our results demonstrate that, while introns are dispensable for cell viability, some introns have diverse roles, such as ensuring proper growth under various conditions and controlling the appropriate anticodon modifications for accurate pairing with the codon.