文章基本信息

标题：Micrococcus luteus DNA gyrase: active components and a model for its supercoiling of DNA
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作者：L F Liu ; J C Wang
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1978
卷号：75
期号：5
页码：2098-2102
DOI：10.1073/pnas.75.5.2098
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Two active components alpha and beta of micrococcus luteus DNA gyrase, of peptide weights of 115,000 and 97,000, respectively, have been purified. Each individual component exhibits little DNA gyrase activity; the ATP-dependent negative supercoiling of a covalently closed circular DNA duplex is catalyzed by a combination of the two. Covalent closure by Escherichia coli ligase of a circular DNA containing single-chain scissions, when carried out in the presence of a combination of the DNA gyrase components alpha and beta, gives a positively supercoiled DNA upon removal of the bound protein molecules. ATP was not present during the ligase treatment; therefore the positive supercoiling of DNA observed is a result of the binding of gyrase molecules, presumably as multi-subunit oligomers, during the ligation step. This is in contrast to the negative supercoiling of DNA catalyzed by gyrase in the presence of ATP. A model in which negative supercoiling of DNA is achieved by ATP-modulated repetitive wrapping of the DNA around gyrase is described. The model also suggests a plausible mode of action by which translocation of a DNA along its helix axis can be actively driven by an ATPase.