Cytoplasmic splicing of tRNA in Saccharomyces cerevisiae
Cytoplasmic splicing of tRNA in Saccharomyces cerevisiae
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DOI：
10.1111/j.1365-2443.2007.01056.x
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发表时间：
2007-03
期刊：
影响因子：
2.1
通讯作者：
T. Yoshihisa;C. Ohshima;Kaori Yunoki-Esaki;T. Endo
中科院分区：
文献类型：
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作者：
T. Yoshihisa;C. Ohshima;Kaori Yunoki-Esaki;T. Endo
核编码RNA（包括tRNA）的剪接已被广泛认为发生在核中。然而，我们最近发现，tRNA剪接酶之一，剪接核酸内切酶，是本地化的线粒体外表面的酿酒酵母。这些结果提示了tRNA在细胞质中剪接的意想不到的可能性。为了研究这种可能性，我们检查了细胞质前tRNA是否是体内tRNA成熟的真正中间体。我们分离到了温度敏感（ts）sen 2（HA-sen 2 - 42）的一个新的可逆等位基因，它编码酵母剪接内切核酸酶催化亚基之一的突变形式。在限制性温度下，HA‐ sen 2 ‐42细胞在细胞质中积累了大量的前tRNA，但当细胞转移到允许温度时，前tRNA减少。使用脉冲追踪/混合沉淀技术，我们发现在允许温度下孵育期间，前tRNA没有降解，而是转化为成熟的tRNA。这些结果表明，在S.在酿酒酵母中，细胞质中的前tRNA是剪接的真正底物，并且剪接确实在细胞质中进行。
The splicing of nuclear encoded RNAs, including tRNAs, has been widely believed to occur in the nucleus. However, we recently found that one of the tRNA splicing enzymes, splicing endonuclease, is localized to the outer surface of mitochondria in Saccharomyces cerevisiae. These results suggested the unexpected possibility of tRNA splicing in the cytoplasm. To investigate this possibility, we examined whether cytoplasmic pre‐tRNAs are bona fide intermediates for tRNA maturation in vivo. We isolated a new reversible allele of temperature‐sensitive (ts) sen2 (HA‐sen2‐42), which encodes a mutant form of one of the catalytic subunits of yeast splicing endonuclease. The HA‐sen2‐42 cells accumulated large amounts of pre‐tRNAs in the cytoplasm at a restrictive temperature, but the pre‐tRNAs were diminished when the cells were transferred to a permissive temperature. Using pulse‐chase/hybrid‐precipitation techniques, we showed that the pre‐tRNAs were not degraded but rather converted into mature tRNAs during incubation at the permissive temperature. These and other results indicate that, in S. cerevisiae, pre‐tRNAs in the cytoplasm are genuine substrates for splicing, and that the splicing is indeed carried out in the cytoplasm.