Possibility of cytoplasmic pre-tRNA splicing: the yeast tRNA splicing endonuclease mainly localizes on the mitochondria.
Possibility of cytoplasmic pre-tRNA splicing: the yeast tRNA splicing endonuclease mainly localizes on the mitochondria.
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DOI：
10.1091/mbc.e02-11-0757
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发表时间：
2003-08
影响因子：
3.3
通讯作者：
T. Yoshihisa;Kaori Yunoki-Esaki;C. Ohshima;N. Tanaka;T. Endo
中科院分区：
文献类型：
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作者：
T. Yoshihisa;Kaori Yunoki-Esaki;C. Ohshima;N. Tanaka;T. Endo
前tRNA剪接被认为发生在细胞核中。在酵母中，切割前tRNA的外显子-内含子连接的tRNA剪接内切酶由Sen 54 p、Sen 2 p、Sen 34 p和Sen 15 p组成，并且被认为是内核被膜的完整膜蛋白。在这里，我们表明，大多数的Sen 2 p，Sen 54 p，和核酸内切酶的活性不位于细胞核中，但在线粒体表面。核酸内切酶与线粒体外膜的胞质表面外周相关。人工固定在线粒体上的Sen 54 p衍生物作为一个完整的膜蛋白可以在功能上取代真正的Sen 54 p，而突变体蛋白在线粒体定位缺陷不完全活跃。sen 2突变细胞在限制性条件下在胞质溶胶中积累未剪接的前-tRNA，并且这种前-tRNA的输出部分依赖于Los 1 p，酵母输出蛋白-t。从tRNA在细胞核中剪接的角度很难解释这些结果。相反，我们提出了一种新的可能性，tRNA剪接发生在酵母线粒体表面。
Pre-tRNA splicing has been believed to occur in the nucleus. In yeast, the tRNA splicing endonuclease that cleaves the exon-intron junctions of pre-tRNAs consists of Sen54p, Sen2p, Sen34p, and Sen15p and was thought to be an integral membrane protein of the inner nuclear envelope. Here we show that the majority of Sen2p, Sen54p, and the endonuclease activity are not localized in the nucleus, but on the mitochondrial surface. The endonuclease is peripherally associated with the cytosolic surface of the outer mitochondrial membrane. A Sen54p derivative artificially fixed on the mitochondria as an integral membrane protein can functionally replace the authentic Sen54p, whereas mutant proteins defective in mitochondrial localization are not fully active. sen2 mutant cells accumulate unspliced pre-tRNAs in the cytosol under the restrictive conditions, and this export of the pre-tRNAs partly depends on Los1p, yeast exportin-t. It is difficult to explain these results from the view of tRNA splicing in the nucleus. We rather propose a new possibility that tRNA splicing occurs on the mitochondrial surface in yeast.