Bailey Scott, Wing Richard A, Steitz Thomas A
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
Cell. 2006 Sep 8;126(5):893-904. doi: 10.1016/j.cell.2006.07.027.
The crystal structure of Thermus aquaticus DNA polymerase III alpha subunit reveals that the structure of the catalytic domain of the eubacterial replicative polymerase is unrelated to that of the eukaryotic replicative polymerase but rather belongs to the Polbeta-like nucleotidyltransferase superfamily. A model of the polymerase complexed with both DNA and beta-sliding clamp interacting with a reoriented binding domain and internal beta binding site was constructed that is consistent with existing biochemical data. Within the crystal, two C-terminal domains are interacting through a surface that is larger than many dimer interfaces. Since replicative polymerases of eubacteria and eukaryotes/archaea are not homologous, the nature of the replicative polymerase in the last common ancestor is unknown. Although other possibilities have been proposed, the plausibility of a ribozyme DNA polymerase should be considered.
嗜热水生栖热菌DNA聚合酶IIIα亚基的晶体结构表明，真细菌复制性聚合酶催化结构域的结构与真核生物复制性聚合酶的结构无关，而是属于Polβ样核苷酸转移酶超家族。构建了一个与DNA和β滑动夹复合物结合的聚合酶模型，该模型与重新定向的结合结构域和内部β结合位点相互作用，这与现有的生化数据一致。在晶体中，两个C末端结构域通过一个比许多二聚体界面都大的表面相互作用。由于真细菌和真核生物/古细菌的复制性聚合酶不同源，所以最后一个共同祖先中复制性聚合酶的性质尚不清楚。尽管已经提出了其他可能性，但应考虑核酶DNA聚合酶的合理性。
