Mitochondrial DNA polymerase gamma is expressed and translated in the absence of mitochondrial DNA maintenance and replication
Mitochondrial DNA polymerase gamma is expressed and translated in the absence of mitochondrial DNA maintenance and replication
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DOI：
10.1093/nar/24.14.2753
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发表时间：
1996-07-15
影响因子：
14.9
通讯作者：
Copeland, WC
中科院分区：
文献类型：
--
作者：
Davis, AF;Ropp, PA;Copeland, WC
线粒体是所有真核细胞中必不可少的细胞器，其中细胞ATP通过氧化磷酸化过程产生。呼吸组装的蛋白质组分是线粒体和核基因的基因产物。线粒体基因组本身编码这种氧化磷酸化过程所需的几种蛋白质和核酸组分，但编码呼吸链组分的绝大多数基因是核基因。类似地，线粒体DNA的复制和转录过程完全依赖于由核基因编码的RNA和蛋白质种类，我们已经分析了两个关键的核编码蛋白参与线粒体DNA的复制和转录作为一个功能的存在或缺乏的线粒体DNA，线粒体DNA聚合酶（DNA聚合酶γ），合成mtDNA的核编码酶，在缺乏线粒体DNA本身的细胞中表达和翻译，相反，线粒体转录因子A蛋白水平与细胞的mtDNA状态紧密相关。这些结果证明DNA聚合酶γ蛋白在线粒体DNA不存在时是稳定的，并且在完全不存在线粒体DNA的情况下，这些细胞中似乎没有调节机制来改变这种蛋白质的水平。或者，这种酶可能在细胞中发挥额外的、尚未确定的作用，从而强制其继续产生。
Mitochondria are essential organelles in all eukaryotic cells where cellular ATP is generated through the process of oxidative phosphorylation. Protein components of the respiratory assembly are gene products of both mitochondrial and nuclear genes, The mitochondrial genome itself encodes several protein and nucleic acid components required for such oxidative phosphorylative processes, but the vast majority of genes encoding respiratory chain components are nuclear, Similarly, the processes of replication and transcription of mitochondrial DNA rely exclusively upon RNA and protein species encoded by nuclear genes, We have analyzed two key nuclear-encoded proteins involved in mitochondrial DNA replication and transcription as a function of the presence or absence of mitochondrial DNA, Mitochondrial DNA polymerase (DNA polymerase gamma), the nuclear-encoded enzyme which synthesizes mtDNA, is expressed and translated in cells devoid of mitochondrial DNA itself, In contrast, mitochondrial transcription factor A protein levels are tightly linked to the mtDNA status of the cell, These results demonstrate that the DNA polymerase gamma protein is stable in the absence of mitochondrial DNA, and that there appears to be no regulatory mechanism present in these cells to alter levels of this protein in the complete absence of mitochondrial DNA, Alternatively it is possible that this enzyme plays an additional, as yet undefined, role in the cell, thereby mandating its continued production.