Sugino A, Higgins N P, Cozzarelli N R
Nucleic Acids Res. 1980 Sep 11;8(17):3865-74. doi: 10.1093/nar/8.17.3865.
Escherichia coli DNA gyrase contains a 1:1 ratio of protomers coded by the genes gyrA and gyrB. This along with previous results shows that the enzyme has two copies of each protomer and thus a molecular weight of 400,000. Abortion of the gyrase reaction results in double-strand breakage of the DNA and covalent attachment of both gyrA protomers to the 5'-cut ends. We conclude that the gyrA protomer contains a critical part of the active site for the concerted breakage and reunion reaction of gyrase, the topoisomerase activity of the enzyme.
大肠杆菌DNA促旋酶包含由gyrA和gyrB基因编码的原聚体，其比例为1:1。这与先前的结果表明，该酶每个原聚体有两个拷贝，因此分子量为400,000。促旋酶反应的终止导致DNA双链断裂以及两个gyrA原聚体与5'-切割末端的共价连接。我们得出结论，gyrA原聚体包含促旋酶协同断裂和重连反应（即该酶的拓扑异构酶活性）活性位点的关键部分。
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