Crystal Structure of the Human Primase
Crystal Structure of the Human Primase
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DOI：
10.1074/jbc.m114.624742
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发表时间：
2015-02-27
影响因子：
4.8
通讯作者：
Tahirov, Tahir H.
中科院分区：
文献类型：
--
作者：
Baranovskiy, Andrey G.;Zhang, Yinbo;Tahirov, Tahir H.
细菌和真核生物的DNA复制需要DNA引物酶的活性，DNA引物酶是一种依赖DNA的RNA聚合酶，为DNA聚合酶提供短RNA引物。真核生物和古细菌引物是由小催化亚基和大辅助亚基组成的异源二聚体，两者都是RNA引物合成所必需的。由于缺乏全长引物酶及其与底物在起始和延伸状态下的复合物的晶体结构，目前对真核生物RNA合成引物的了解有限。在这里，我们报道了全长人引物酶的晶体结构，揭示了酶的精确整体组织，其功能域的相对位置，以及它与模型DNA和RNA相互作用的模式。该结构表明，引物酶的巨大构象变化是完成RNA合成起始和延伸所必需的。p58的N端和c端结构域之间存在一个长连接体，为酶的大部分构象灵活性提供了结构基础。该连接体的大部分缺失影响了引物合成的起始和延伸步骤。
DNA replication in bacteria and eukaryotes requires the activity of DNA primase, a DNA-dependent RNA polymerase that lays short RNA primers for DNA polymerases. Eukaryotic and archaeal primases are heterodimers consisting of small catalytic and large accessory subunits, both of which are necessary for RNA primer synthesis. Understanding of RNA synthesis priming in eukaryotes is currently limited due to the lack of crystal structures of the full-length primase and its complexes with substrates in initiation and elongation states. Here we report the crystal structure of the full-length human primase, revealing the precise overall organization of the enzyme, the relative positions of its functional domains, and the mode of its interaction with modeled DNA and RNA. The structure indicates that the dramatic conformational changes in primase are necessary to accomplish the initiation and then elongation of RNA synthesis. The presence of a long linker between the N- and C-terminal domains of p58 provides the structural basis for the bulk of enzyme's conformational flexibility. Deletion of most of this linker affected the initiation and elongation steps of the primer synthesis.