The crystal structure of the complex of replication protein A subunits RPA32 and RPA14 reveals a mechanism for single-stranded DNA binding
The crystal structure of the complex of replication protein A subunits RPA32 and RPA14 reveals a mechanism for single-stranded DNA binding
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DOI：
10.1093/emboj/18.16.4498
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发表时间：
1999-08-16
期刊：
影响因子：
11.4
通讯作者：
Edwards, AM
中科院分区：
文献类型：
--
作者：
Bochkarev, A;Bochkareva, E;Edwards, AM
复制蛋白A（RPA）是真核生物单链DNA结合蛋白（SSB），是一种异源三聚体。RPA 70具有两个DNA结合结构域，每个结构域采用OB折叠，RPA 32和RPA 14两个较小的亚基的复合物具有弱的DNA结合活性，但DNA结合机制尚不清楚。我们测定了RPA 32和RPA 14的蛋白水解核心的晶体结构，它由RPA 32的中心三分之二和整个RPA 14亚基组成，结构表明RPA 14和RPA 32的中心部分是结构同源物。每个亚基包含一个中心OB折叠结构域，它也类似于RPA 70中的DNA结合结构域;一个与中心OB折叠结构域相互作用的N末端延伸; RPA 32的OB折叠，而不是RPA 14，具有与RPA 70 DNA结合结构域的额外相似性，支持RPA 32的DNA结合作用，RPA中第三和第四个OB-折叠的发现表明SSB的四级结构在进化中是保守的，SSB在细菌和细菌中也是OB-折叠的四聚体。该结构还表明RPA三聚体形成的机制。
Replication protein A (RPA), the eukaryote single-stranded DNA-binding protein (SSB), is a heterotrimer. The largest submit, RPA70, which harbours the major DNA-binding activity, has two DNA-binding domains that each adopt an OB-fold, The complex of the two smaller subunits, RPA32 and RPA14, has weak DNA-binding activity but the mechanism of DNA binding is unknown. We have determined the crystal structure of the proteolytic core of RPA32 and RPA14, which consists of the central two-thirds of RPA32 and the entire RPA14 subunit, The structure revealed that RPA14 and the central part of RPA32 are structural homologues. Each subunit contains a central OB-fold domain, which also resembles the DNA-binding domains in RPA70; an N-terminal extension that interacts with the central OB-fold domain; and a C-terminal helix that mediate heterodimerization via a helix-helix interaction, The OB-fold of RPA32, but not RPA14, possesses additional similarity to the RPA70 DNA-binding domains, supporting a DNA-binding role for RPA32, The discovery of a third and fourth OB-fold in RPA suggests that the quaternary structure of SSBs, which in Bacteria and Archaea are also tetramers of OB-folds, is conserved in evolution. The structure also suggests a mechanism for RPA trimer formation.