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首页> 外文期刊>Molecular and Cellular Biology >The mitochondrial tyrosyl-tRNA synthetase of Podospora anserina is a bifunctional enzyme active in protein synthesis and RNA splicing.
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The mitochondrial tyrosyl-tRNA synthetase of Podospora anserina is a bifunctional enzyme active in protein synthesis and RNA splicing.

机译：Podospora anserina的线粒体酪氨酰-tRNA合成酶是一种在蛋白质合成和RNA剪接中具有活性的双功能酶。

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The Neurospora crassa mitochondrial tyrosyl-tRNA synthetase (mt tyrRS), which is encoded by the nuclear gene cyt-18, functions not only in aminoacylation but also in the splicing of group I introns. Here, we isolated the cognate Podospora anserina mt tyrRS gene, designated yts1, by using the N. crassa cyt-18 gene as a hybridization probe. DNA sequencing of the P. anserina gene revealed an open reading frame (ORF) of 641 amino acids which has significant similarity to other tyrRSs. The yts1 ORF is interrupted by two introns, one near its N terminus at the same position as the single intron in the cyt-18 gene and the other downstream in a region corresponding to the nucleotide-binding fold. The P. anserina yts1+ gene transformed the N. crassa cyt-18-2 mutant at a high frequency and rescued both the splicing and protein synthesis defects. Furthermore, the YTS1 protein synthesized in Escherichia coli was capable of splicing the N. crassa mt large rRNA intron in vitro. Together, these results indicate that YTS1 is a bifunctional protein active in both splicing and protein synthesis. The P. anserina YTS1 and N. crassa CYT-18 proteins share three blocks of amino acids that are not conserved in bacterial or yeast mt tyrRSs which do not function in splicing. One of these blocks corresponds to the idiosyncratic N-terminal domain shown previously to be required for splicing activity of the CYT-18 protein. The other two are located in the putative tRNA-binding domain toward the C terminus of the protein and also appear to be required for splicing. Since the E. coli and yeast mt tyrRSs do not function in splicing, the adaptation of the Neurospora and Podospora spp. mt tyrRSs to function in splicing most likely occurred after the divergence of their common ancestor from yeast.
机译：核基因cyt-18编码的神经孢霉线粒体酪氨酰tRNA合成酶（mt tyrRS），不仅在氨基酰化中起作用，而且在I组内含子的剪接中也起作用。在这里，我们通过使用N. crassa cyt-18基因作为杂交探针分离了同源的Popospora anserina mt tyrRS基因，命名为yts1。 P. anserina基因的DNA测序揭示了一个641个氨基酸的开放阅读框（ORF），该阅读框与其他tyrRS显着相似。 yts1 ORF被两个内含子中断，一个内含子在N末端附近，与cyt-18基因中的单个内含子在同一位置，另一个在与核苷酸结合折叠相对应的区域的下游。 P. anserina yts1 +基因以高频率转化了N. crassa cyt-18-2突变体，并挽救了剪接和蛋白质合成缺陷。此外，在大肠杆菌中合成的YTS1蛋白能够在体外剪接猪笼草的大型rRNA内含子。总之，这些结果表明YTS1是一种在剪接和蛋白质合成中均具有活性的双功能蛋白质。 P. anserina YTS1和N. crassa CYT-18蛋白共有三个氨基酸块，这些氨基酸在细菌或酵母mt tyrRSs中不保守，在剪接中不起作用。这些嵌段之一对应于先前显示的CYT-18蛋白的剪接活性所需的特异N末端结构域。另外两个位于推定的tRNA结合结构域中，朝向蛋白质的C末端，并且似乎也是剪接所必需的。由于大肠杆菌和酵母mt tyrRS在剪接中不起作用，因此对神经孢菌属和鲍氏孢子菌的适应性强。 mt tyrRSs最有可能在剪接中发挥作用，它们的共同祖先与酵母菌不同。

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