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首页> 外文期刊>Biochemistry >A NONCANONICAL TERTIARY CONFORMATION OF A HUMAN MITOCHONDRIAL TRANSFER RNA
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A NONCANONICAL TERTIARY CONFORMATION OF A HUMAN MITOCHONDRIAL TRANSFER RNA

机译:人线粒体转移RNA的非典范构象

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摘要

Transfer RNAs possess highly conserved secondary structures, and crystallographic studies suggest a common, L-shaped tertiary conformation in which the anticodon and acceptor stems are disposed at approximately right angles to one another. However, many animal mitochondrial tRNAs possess unusual secondary structures, and little is known regarding their tertiary conformations, in particular, the relative orientations of their- acceptor and anticodon stems. To address this issue, we have constructed heteroduplex RNA molecules corresponding to human mitochondrial and cytoplasmic lysyl tRNAs in which the acceptor and anticodon stems of each tRNA have been extended by approximately 70 base pairs. The rotational decay times of the two ''extended'' tRNA(Lys) species were compared to the decay times of a linear RNA control and to an extended yeast cytoplasmic tRNA(Phe) species whose interstem angle had been reported previously. Whereas the apparent interstem angle of the human cytoplasmic tRNA(Lys) species is essentially identical to that of the yeast tRNA(Phe) heteroduplex, with both conforming to the canonical L-shape, the angle for the mitochondrial tRNA(Lys) construct is much larger (similar to 140 degrees). Thus, the universal L-shape may not be applicable to noncanonical mitochondrial tRNAs, a finding of significance for both tRNA evolution and mitochondrial disease.
机译:转移RNA具有高度保守的二级结构,晶体学研究表明,一种常见的L形三级构象,其中反密码子和受体茎彼此之间大致成直角。但是,许多动物线粒体tRNA具有不寻常的二级结构,对其三级构象,尤其是其受体和反密码子茎的相对方向了解甚少。为了解决这个问题,我们构建了对应于人类线粒体和胞质赖氨酰tRNA的异源双链RNA分子,其中每个tRNA的受体和反密码子茎已延伸了约70个碱基对。将两个“延伸的” tRNA(Lys)物种的旋转衰减时间与线性RNA对照的衰减时间以及与先前已报道其间角的延伸的酵母胞质tRNA(Phe)物种进行了比较。尽管人类细胞质tRNA(Lys)物种的表观间角与酵母tRNA(Phe)异源双链体的表观间角基本相同,并且两者均符合规范的L形,但线粒体tRNA(Lys)构建体的角度却很大更大(类似于140度)。因此,通用的L形可能不适用于非规范的线粒体tRNA,这对于tRNA进化和线粒体疾病均具有重要意义。

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