Prevention of mitochondrial genomic instability in yeast by the mitochondrial recombinase Mhr1
Prevention of mitochondrial genomic instability in yeast by the mitochondrial recombinase Mhr1
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DOI：
10.1038/s41598-019-41699-9
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发表时间：
2019-04-01
影响因子：
4.6
通讯作者：
Minoru, Yoshida
中科院分区：
文献类型：
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作者：
Ling, Feng;Bradshaw, Elliot;Minoru, Yoshida
线粒体（mt）DNA编码细胞呼吸所必需的因子，因此其水平和完整性至关重要。ABF 2编码线粒体DNA结合蛋白，其无效突变（Δ abf 2）在酿酒酵母中诱导线粒体DNA不稳定。Mhr 1是一种线粒体重组酶，介导mtDNA复制的主要形式，并在mtDNA分离和mtDNA双链断裂（DSB）的修复中起作用。然而，Mhr 1参与防止mtDNA缺失突变是未知的。在这项研究中，我们使用Delta abf 2 mhr 1 -1双突变细胞，在含有可发酵碳源的培养基中失去线粒体功能，以调查Mhr 1是否是mtDNA缺失突变的抑制因子。我们使用了抑制性试验和Southern印迹分析来揭示Delta abf 2突变导致mtDNA缺失，而不是mtDNA缺失（rho（0））表型，并观察到mtDNA缺失因额外的mhr 1 -1突变而加剧。在Delta mhr 1和Delta abf 2 mhr 1 -1细胞中，由于mtDNA片段化而导致呼吸功能丧失。然而，Mhr 1到Delta abf 2 mhr 1 -1细胞的外源性引入显着拯救呼吸生长，这表明Mhr 1驱动的同源mtDNA重组防止mtDNA不稳定。
Mitochondrial (mt) DNA encodes factors essential for cellular respiration, therefore its level and integrity are crucial. ABF2 encodes a mitochondrial DNA-binding protein and its null mutation (Delta abf2) induces mtDNA instability in Saccharomyces cerevisiae. Mhr1 is a mitochondrial recombinase that mediates the predominant form of mtDNA replication and acts in mtDNA segregation and the repair of mtDNA double-stranded breaks (DSBs). However, the involvement of Mhr1 in prevention of mtDNA deletion mutagenesis is unknown. In this study we used Delta abf2 mhr1-1 double-mutant cells, which lose mitochondrial function in media containing fermentable carbon sources, to investigate whether Mhr1 is a suppressor of mtDNA deletion mutagenesis. We used a suppresivity assay and Southern blot analysis to reveal that the Delta abf2 mutation causes mtDNA deletions rather than an mtDNA-lacking (rho(0)) phenotype, and observed that mtDNA deletions are exacerbated by an additional mhr1-1 mutation. Loss of respiratory function due to mtDNA fragmentation occurred in Delta mhr1 and Delta abf2 mhr1-1 cells. However, exogenous introduction of Mhr1 into Delta abf2 mhr1-1 cells significantly rescued respiratory growth, suggesting that Mhr1-driven homologous mtDNA recombination prevents mtDNA instability.