Tse-Dinh Y C
Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, NY 10595, USA.
Biochim Biophys Acta. 1998 Oct 1;1400(1-3):19-27. doi: 10.1016/s0167-4781(98)00125-0.
Bacterial and archeal type I topoisomerases, including topoisomerase I, topoisomerase III and reverse gyrase, have different potential roles in the control of DNA topology including regulation of supercoiling and maintenance of genetic stability. Analysis of their coding sequences in different organisms shows that they belong to the type IA family of DNA topoisomerases, but there is variability in organization of various enzymatic domains necessary for topoisomerase activity. The torus-like structure of the conserved transesterification domain with the active site tyrosine for DNA cleavage/rejoining suggests steps of enzyme conformational change driven by DNA substrate and Mg(II) cofactor binding, that are required for catalysis of change in DNA linking number.
细菌和古菌的I型拓扑异构酶，包括拓扑异构酶I、拓扑异构酶III和反向回旋酶，在DNA拓扑结构的控制中具有不同的潜在作用，包括超螺旋调节和遗传稳定性维持。对不同生物体中它们编码序列的分析表明，它们属于DNA拓扑异构酶IA家族，但拓扑异构酶活性所需的各种酶结构域的组织存在差异。具有用于DNA切割/重新连接的活性位点酪氨酸的保守转酯结构域的环形结构表明，由DNA底物和Mg(II)辅因子结合驱动的酶构象变化步骤是催化DNA连接数变化所必需的。
