Center for Eukaryotic Structural Genomics, Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Korea.
Proteins. 2013 Sep;81(9):1669-1675. doi: 10.1002/prot.24315. Epub 2013 Jun 17.
Arabidopsis thaliana gene At5g06450 encodes a putative DnaQ-like 3'-5' exonuclease domain-containing protein (AtDECP). The DnaQ-like 3'-5' exonuclease domain is often found as a proofreading domain of DNA polymerases. The overall structure of AtDECP adopts an RNase H fold that consists of a mixed β-sheet flanked by α-helices. Interestingly, AtDECP forms a homohexameric assembly with a central six fold symmetry, generating a central cavity. The ring-shaped structure and comparison with WRN-exo, the best structural homologue of AtDECP, suggest a possible mechanism for implementing its exonuclease activity using positively charged patch on the N-terminal side of the homohexameric assembly. The homohexameric structure of AtDECP provides unique information about the interaction between the DnaQ-like 3'-5' exonuclease and its substrate nucleic acids.
拟南芥基因 At5g06450 编码一种假定的 DnaQ 样 3'-5'外切酶结构域包含蛋白（AtDECP）。DnaQ 样 3'-5'外切酶结构域通常作为 DNA 聚合酶的校对结构域存在。AtDECP 的整体结构采用 RNase H 折叠，由一个混合的β-sheet 侧翼的α-helices 组成。有趣的是，AtDECP 形成一个具有中央六重对称的同六聚体组装，产生一个中央腔。环形结构以及与 WRN-exo 的比较，WRN-exo 是 AtDECP 的最佳结构同源物，提示了一种可能的机制，即利用同六聚体组装的 N 端正电荷斑来实现其外切酶活性。AtDECP 的同六聚体结构为 DnaQ 样 3'-5'外切酶与其底物核酸之间的相互作用提供了独特的信息。
