Diversity of DNA Replication in the Archaea.
Diversity of DNA Replication in the Archaea.
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DOI：
10.3390/genes8020056
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发表时间：
2017-01-31
期刊：
影响因子：
3.5
通讯作者：
Allers T
中科院分区：
文献类型：
--
作者：
Ausiannikava D;Allers T
DNA复制可以说是最基本的生物过程。由于它们有着共同的进化祖先，在古细菌中发现的复制机制与真核生物中发现的相似。DNA复制起始于起始点，在真核生物中高度保守，但我们对古生菌的有限了解揭示了广泛多样的复制起始机制。微生物起源是基于序列的，如在细菌中，但被与真核生物起源识别复合物亚基Orc 1和解旋酶加载器Cdc 6共享同源性的起始蛋白结合。与细菌不同的是，古生菌可能每个染色体有多个起源和多个Orc 1/Cdc 6起始蛋白。关于这些古细菌的起源是如何被消除的还没有达成共识-有些是由单个Orc 1/Cdc 6蛋白结合的，而另一些则需要多个Orc 1/Cdc 6复合物。许多古细菌的基因组由多个部分组成--主染色体加上几个巨质粒--在多倍体物种中，这些部分以多个拷贝存在。这对DNA复制的调控提出了挑战。然而，有一种古细菌（Haloferax volcano ii）可以在没有复制起点的情况下生存，而是使用同源重组作为启动的替代机制。这种DNA复制起始的多样性更值得注意的是，只有三组古生菌中发现了这种多样性，而体内研究是可能的。
DNA replication is arguably the most fundamental biological process. On account of their shared evolutionary ancestry, the replication machinery found in archaea is similar to that found in eukaryotes. DNA replication is initiated at origins and is highly conserved in eukaryotes, but our limited understanding of archaea has uncovered a wide diversity of replication initiation mechanisms. Archaeal origins are sequence-based, as in bacteria, but are bound by initiator proteins that share homology with the eukaryotic origin recognition complex subunit Orc1 and helicase loader Cdc6). Unlike bacteria, archaea may have multiple origins per chromosome and multiple Orc1/Cdc6 initiator proteins. There is no consensus on how these archaeal origins are recognised—some are bound by a single Orc1/Cdc6 protein while others require a multi- Orc1/Cdc6 complex. Many archaeal genomes consist of multiple parts—the main chromosome plus several megaplasmids—and in polyploid species these parts are present in multiple copies. This poses a challenge to the regulation of DNA replication. However, one archaeal species (Haloferax volcanii) can survive without replication origins; instead, it uses homologous recombination as an alternative mechanism of initiation. This diversity in DNA replication initiation is all the more remarkable for having been discovered in only three groups of archaea where in vivo studies are possible.