Phage origin of mitochondrion-localized family A DNA polymerases in kinetoplastids and diplonemids

Mitochondria retain their own genomes as other bacterial endosymbiont-derived organelles. Nevertheless, no protein for DNA replication and repair is encoded in any mitochondrial genomes (mtDNAs) assessed to date, suggesting the nucleus primarily governs the maintenance of mtDNA. As the proteins of diverse evolutionary origins occupy a large proportion of the current mitochondrial proteomes, we anticipate finding the same evolutionary trend in the nucleus-encoded machinery for mtDNA maintenance. Indeed, none of the DNA polymerases (DNAPs) in the mitochondrial endosymbiont, a putative α-proteobacterium, seemingly had been inherited by their descendants (mitochondria), as none of the known types of mitochondrion-localized DNAP showed a specific affinity to the α-proteobacterial DNAPs. Nevertheless, we currently have no concrete idea of how and when the known types of mitochondrion-localized DNAPs emerged. We here explored the origins of mitochondrion-localized DNAPs after the improvement o...与其他源自细菌内共生体的细胞器一样，线粒体拥有自身的基因组。然而，截至目前所有已评估的线粒体基因组（mtDNAs）中，均未编码任何参与DNA复制与修复的蛋白质，这提示细胞核主导了线粒体基因组的维持过程。由于当前线粒体蛋白质组中很大一部分蛋白质的进化来源各不相同，我们推测在细胞核编码的线粒体基因组维持机制中，也存在同样的进化趋势。事实上，线粒体的内共生祖先——一种推定的α-变形菌门细菌（α-proteobacterium）——的DNA聚合酶（DNAPs）似乎并未被其后代（线粒体）所继承：目前已知的所有定位于线粒体的DNA聚合酶，均未表现出与α-变形菌门DNA聚合酶的特异性同源性。然而，目前我们尚不清楚已知的定位于线粒体的DNA聚合酶究竟是如何、何时起源的。本研究针对定位于线粒体的DNA聚合酶的起源展开了探究，相关工作在经过改进后o...