Din7 and Mhr1 expression levels regulate double-strand-break-induced replication and recombination of mtDNA at ori5 in yeast.
Din7 and Mhr1 expression levels regulate double-strand-break-induced replication and recombination of mtDNA at ori5 in yeast.
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DOI：
10.1093/nar/gkt273
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发表时间：
2013-06
影响因子：
14.9
通讯作者：
Shibata T
中科院分区：
文献类型：
--
作者：
Ling F;Hori A;Yoshitani A;Niu R;Yoshida M;Shibata T
Ntg1和Mhr1蛋白启动滚环线粒体DNA复制以实现同质性，并诱导同源重组以维持线粒体基因组的完整性。虽然复制和重组深刻地影响线粒体遗传，但决定这些途径之间选择的调节机制仍然未知。在酿酒酵母中，Ntg1在线粒体复制起始处引入的双链断裂(DSB)通过Mhr1诱导同源DNA配对，而活性氧(ROS)促进DSB的产生。在这里，我们证明了由核基因DIN7(DNA损伤诱导基因)编码的线粒体核酸酶具有5‘-外脱氧核糖核酸酶活性。以含ORI5(超抑制；HS)的小ρ−线粒体DNA为模型，我们发现DIN7是ROS增强的线粒体DNA复制和重组所必需的，这两种复制和重组都是在ORI5诱导的。在HS-ρ−细胞中，Din7的过量生产增加了依赖于Mhr1的线粒体DNA的复制，增加了在ORI5处残留的DSB的数量，并增加了ρ+细胞中ORI5区的缺失突变。然而，同时过量生产的Mhr1抑制了所有这些表型并促进了同源重组。我们的结果表明，在同源配对后，Din7和Mhr1的相对活性水平调节了对复制的偏好，而不是同源重组来修复ORI5处的DSB。
The Ntg1 and Mhr1 proteins initiate rolling-circle mitochondrial (mt) DNA replication to achieve homoplasmy, and they also induce homologous recombination to maintain mitochondrial genome integrity. Although replication and recombination profoundly influence mitochondrial inheritance, the regulatory mechanisms that determine the choice between these pathways remain unknown. In Saccharomyces cerevisiae, double-strand breaks (DSBs) introduced by Ntg1 at the mitochondrial replication origin ori5 induce homologous DNA pairing by Mhr1, and reactive oxygen species (ROS) enhance production of DSBs. Here, we show that a mitochondrial nuclease encoded by the nuclear gene DIN7 (DNA damage inducible gene) has 5′-exodeoxyribonuclease activity. Using a small ρ− mtDNA bearing ori5 (hypersuppressive; HS) as a model mtDNA, we revealed that DIN7 is required for ROS-enhanced mtDNA replication and recombination that are both induced at ori5. Din7 overproduction enhanced Mhr1-dependent mtDNA replication and increased the number of residual DSBs at ori5 in HS-ρ− cells and increased deletion mutagenesis at the ori5 region in ρ+ cells. However, simultaneous overproduction of Mhr1 suppressed all of these phenotypes and enhanced homologous recombination. Our results suggest that after homologous pairing, the relative activity levels of Din7 and Mhr1 modulate the preference for replication versus homologous recombination to repair DSBs at ori5.
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影响因子：
11.4
作者：
LING, F;MAKISHIMA, F;SHIBATA, T
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影响因子：
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