Evidence for double-strand break mediated mitochondrial DNA replication in Saccharomyces cerevisiae.
Evidence for double-strand break mediated mitochondrial DNA replication in Saccharomyces cerevisiae.
复制标题
酿酒酵母中双链断裂介导的线粒体DNA复制的证据。
DOI：
10.1093/nar/gkx443
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发表时间：
2017-07-27
影响因子：
14.9
通讯作者：
Harrison L
中科院分区：
文献类型：
--
作者：
Prasai K;Robinson LC;Scott RS;Tatchell K;Harrison L
酿酒酵母中线粒体DNA（mtDNA）的复制机制一直存在争议。在高抑制性ρ−细胞中，存在双链断裂（DSB）介导的线粒体复制起点ori5处的重组依赖性复制的证据。然而，尚不清楚这种复制模式是否在ρ+细胞中运作。为了理解这一点，我们将细菌Ku（bKu）（一种DSB结合蛋白）靶向ρ+细胞的线粒体，假设bKu将持续结合mtDNA DSB，从而阻止mtDNA复制或修复。在这里，我们表明，尿道靶向bKu结合ori5和诱导表达的bKu触发娇小的形成优先在子细胞。bKu的表达还诱导mtDNA耗竭，最终导致ρ0细胞的形成。这些数据支持酵母mtDNA复制由DSB启动的观点，bKu通过与ori5处的DSB结合来抑制mtDNA复制，从而防止mtDNA分离到子细胞。有趣的是，我们发现靶向骨髓的bKu不会降低人类MCF7细胞中mtDNA的含量。这一发现与人类mtDNA复制通常不是由DSB启动的事实一致。因此，本研究提供了证据，DSB介导的复制是ρ+酵母细胞中mtDNA复制的主要形式。
The mechanism of mitochondrial DNA (mtDNA) replication in Saccharomyces cerevisiae is controversial. Evidence exists for double-strand break (DSB) mediated recombination-dependent replication at mitochondrial replication origin ori5 in hypersuppressive ρ− cells. However, it is not clear if this replication mode operates in ρ+ cells. To understand this, we targeted bacterial Ku (bKu), a DSB binding protein, to the mitochondria of ρ+ cells with the hypothesis that bKu would bind persistently to mtDNA DSBs, thereby preventing mtDNA replication or repair. Here, we show that mitochondrial-targeted bKu binds to ori5 and that inducible expression of bKu triggers petite formation preferentially in daughter cells. bKu expression also induces mtDNA depletion that eventually results in the formation of ρ0 cells. This data supports the idea that yeast mtDNA replication is initiated by a DSB and bKu inhibits mtDNA replication by binding to a DSB at ori5, preventing mtDNA segregation to daughter cells. Interestingly, we find that mitochondrial-targeted bKu does not decrease mtDNA content in human MCF7 cells. This finding is in agreement with the fact that human mtDNA replication, typically, is not initiated by a DSB. Therefore, this study provides evidence that DSB-mediated replication is the predominant form of mtDNA replication in ρ+ yeast cells.
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