A rolling circle replication mechanism produces multimeric lariats of mitochondrial DNA in Caenorhabditis elegans.
A rolling circle replication mechanism produces multimeric lariats of mitochondrial DNA in Caenorhabditis elegans.
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DOI：
10.1371/journal.pgen.1004985
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发表时间：
2015-02
期刊：
影响因子：
4.5
通讯作者：
Hyman BC
中科院分区：
文献类型：
--
作者：
Lewis SC;Joers P;Willcox S;Griffith JD;Jacobs HT;Hyman BC
线粒体DNA（mtDNA）编码几乎所有真核生物所必需的呼吸复合体亚基;因此呼吸能力需要这个分子的忠实复制。然而，其合成的机制仍然存在激烈的争论。在这里，我们已经开发了秀丽隐杆线虫作为一个方便的动物模型的后生动物mtDNA合成的研究。我们证明了C.线虫线粒体DNA的复制完全通过噬菌体样机制，其中多聚体分子从环状模板合成。与以往的哺乳动物研究相比，我们发现，在C。线虫的性腺产生具有多聚体DNA尾部的分支环状的淋巴结结构;我们能够检测到多达四个mtDNA基因组单位长度的多聚体。此外，我们没有检测到7S DNA的置换环或类似物的延伸，这表明在复制起始位点方面与人类mtDNA存在明显差异。我们还确定了十字形的线粒体DNA物种是敏感的裂解的解离酶RusA，我们认为这些四路路口可能有一个作用，在多联体到单体的决议。这些结果表明，C.秀丽线虫不符合任何先前记载的后生动物mtDNA复制机制，而是强烈暗示了噬菌体所采用的滚环复制。由于后生动物线粒体DNA复制体的几个组成部分可能是噬菌体衍生的，这些发现提出了滚动环mtDNA复制机制可能是后生动物中祖先的可能性。编码呼吸复合物蛋白亚基的线粒体DNA（mtDNA）缺陷可能导致人类严重的代谢疾病。这些缺陷通常是由mtDNA合成过程中的错误引起的，这激发了对这一过程的持续研究。秀丽隐杆线虫已被提议作为研究线粒体DNA复制缺陷的模型。本文分析了C.线虫的生殖腺，并证明它是动物中唯一的。初生蠕虫mtDNA形成分支环状的lymphocytes结构，我们建议将最终解决成单体环，主要的分子形式，通过透射电子显微镜和二维凝胶电泳。我们发现C.秀丽隐杆线虫并没有忠实地模仿哺乳动物中的重要性，因为它证明了在动物中维持这种关键DNA的机制的广度和进化可塑性。有趣的是，C.线虫的线粒体DNA复制体与噬菌体高度相似，线粒体DNA复制体的组分被认为来源于噬菌体。因此C.线虫可能作为线粒体DNA合成的模型，因为它发生在古真核生物中。
Mitochondrial DNA (mtDNA) encodes respiratory complex subunits essential to almost all eukaryotes; hence respiratory competence requires faithful duplication of this molecule. However, the mechanism(s) of its synthesis remain hotly debated. Here we have developed Caenorhabditis elegans as a convenient animal model for the study of metazoan mtDNA synthesis. We demonstrate that C. elegans mtDNA replicates exclusively by a phage-like mechanism, in which multimeric molecules are synthesized from a circular template. In contrast to previous mammalian studies, we found that mtDNA synthesis in the C. elegans gonad produces branched-circular lariat structures with multimeric DNA tails; we were able to detect multimers up to four mtDNA genome unit lengths. Further, we did not detect elongation from a displacement-loop or analogue of 7S DNA, suggesting a clear difference from human mtDNA in regard to the site(s) of replication initiation. We also identified cruciform mtDNA species that are sensitive to cleavage by the resolvase RusA; we suggest these four-way junctions may have a role in concatemer-to-monomer resolution. Overall these results indicate that mtDNA synthesis in C. elegans does not conform to any previously documented metazoan mtDNA replication mechanism, but instead are strongly suggestive of rolling circle replication, as employed by bacteriophages. As several components of the metazoan mitochondrial DNA replisome are likely phage-derived, these findings raise the possibility that the rolling circle mtDNA replication mechanism may be ancestral among metazoans. Defects in the mitochondrial DNA (mtDNA) that encodes protein subunits of the respiratory complexes may cause severe metabolic disease in humans. Such defects are often caused by errors during mtDNA synthesis, motivating ongoing studies of this process. The nematode Caenorhabditis elegans has been proposed as a model for the study of mtDNA replication defects. Here we analyze the mechanism of mtDNA synthesis in the C. elegans gonad and demonstrate that it is unique among animals. Nascent worm mtDNA forms branched-circular lariat structures with concatemeric tails that we suggest would ultimately resolve into monomeric circles, the predominant molecular form identified by both transmission electron microscopy and two-dimensional gel electrophoresis. Our discovery that mtDNA replication in C. elegans does not faithfully model that in mammals is significant, because it demonstrates the breadth and evolutionary plasticity of the mechanisms that maintain this critical DNA among animals. Interestingly, the mtDNA replication mechanism within C. elegans is highly similar to that of bacteriophages, from which components of the mitochondrial DNA replisome are thought to be derived. Thus C. elegans may serve as a model for mtDNA synthesis as it occurred within ancient eukaryotes.
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影响因子：
4.5
作者：
Jõers P;Lewis SC;Fukuoh A;Parhiala M;Ellilä S;Holt IJ;Jacobs HT
通讯作者：
Jacobs HT
影响因子：
4.3
作者：
Bratic, Ivana;Trifunovic, Aleksandra
通讯作者：
Trifunovic, Aleksandra
影响因子：
3.7
作者：
Joers, Priit;Jacobs, Howard T.
通讯作者：
Jacobs, Howard T.
影响因子：
1.6
作者：
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通讯作者：
STACHOW, C
影响因子：
16
作者：
Bolt, EL;Lloyd, RG
通讯作者：
Lloyd, RG