大肠杆菌DNA聚合酶III全酶β亚基的三维结构：一种滑动DNA夹

Three-dimensional structure of the beta subunit of E. coli DNA polymerase III holoenzyme: a sliding DNA clamp.

作者信息

Kong X P, Onrust R, O'Donnell M, Kuriyan J

机构信息

Laboratory of Molecular Biophysics, Rockefeller University, New York, New York 10021.

出版信息

Cell. 1992 May 1;69(3):425-37. doi: 10.1016/0092-8674(92)90445-i.

DOI:10.1016/0092-8674(92)90445-i

PMID:1349852

Abstract

The crystal structure of the beta subunit (processivity factor) of DNA polymerase III holoenzyme has been determined at 2.5 A resolution. A dimer of the beta subunit (M(r) = 2 x 40.6 kd, 2 x 366 amino acid residues) forms a ring-shaped structure lined by 12 alpha helices that can encircle duplex DNA. The structure is highly symmetrical, with each monomer containing three domains of identical topology. The charge distribution and orientation of the helices indicate that the molecule functions by forming a tight clamp that can slide on DNA, as shown biochemically. A potential structural relationship is suggested between the beta subunit and proliferating cell nuclear antigen (PCNA, the eukaryotic polymerase delta [and epsilon] processivity factor), and the gene 45 protein of the bacteriophage T4 DNA polymerase.

摘要

已在2.5埃分辨率下测定了DNA聚合酶III全酶β亚基（持续性因子）的晶体结构。β亚基二聚体（相对分子质量=2×40.6kd，2×366个氨基酸残基）形成一种环形结构，由12个α螺旋排列而成，可环绕双链DNA。该结构高度对称，每个单体包含三个拓扑结构相同的结构域。螺旋的电荷分布和取向表明，该分子通过形成一个可在DNA上滑动的紧密夹子发挥作用，这已得到生化实验的证明。有人提出β亚基与增殖细胞核抗原（PCNA，真核生物聚合酶δ[和ε]持续性因子）以及噬菌体T4 DNA聚合酶的基因45蛋白之间可能存在结构关系。