Lamers Meindert H, Georgescu Roxana E, Lee Sang-Gyu, O'Donnell Mike, Kuriyan John
Howard Hughes Medical Institute, Department of Molecular and Cell Biology and Department of Chemistry, University of California, Berkeley, CA 94720, USA.
Cell. 2006 Sep 8;126(5):881-92. doi: 10.1016/j.cell.2006.07.028.
Bacterial replicative DNA polymerases such as Polymerase III (Pol III) share no sequence similarity with other polymerases. The crystal structure, determined at 2.3 A resolution, of a large fragment of Pol III (residues 1-917), reveals a unique chain fold with localized similarity in the catalytic domain to DNA polymerase beta and related nucleotidyltransferases. The structure of Pol III is strikingly different from those of members of the canonical DNA polymerase families, which include eukaryotic replicative polymerases, suggesting that the DNA replication machinery in bacteria arose independently. A structural element near the active site in Pol III that is not present in nucleotidyltransferases but which resembles an element at the active sites of some canonical DNA polymerases suggests that, at a more distant level, all DNA polymerases may share a common ancestor. The structure also suggests a model for interaction of Pol III with the sliding clamp and DNA.
细菌复制性DNA聚合酶，如聚合酶III（Pol III），与其他聚合酶没有序列相似性。以2.3埃分辨率确定的Pol III大片段（残基1 - 917）的晶体结构，揭示了一种独特的链折叠，其催化结构域与DNA聚合酶β及相关核苷酸转移酶存在局部相似性。Pol III的结构与包括真核生物复制性聚合酶在内的典型DNA聚合酶家族成员的结构显著不同，这表明细菌中的DNA复制机制是独立产生的。Pol III活性位点附近的一个结构元件在核苷酸转移酶中不存在，但类似于一些典型DNA聚合酶活性位点的一个元件，这表明在更远的层面上，所有DNA聚合酶可能有一个共同的祖先。该结构还提出了一个Pol III与滑动夹钳和DNA相互作用的模型。
