Escherichia coli DNA topoisomerase I catalyzed linking of single-stranded rings of complementary base sequences
摘要：
Eco DNA topoisomerase I (E. coli omega protein) has been observed to catalyze the formation of double-stranded, covalently closed DNA from complementary single-stranded DNA rings, a novel reaction which is topologically forbidden without the enzyme-catalyzed breakage and rejoining of DNA backbone bonds. Incubation of a mixture of single-stranded PM2 DNA rings of complementary base sequences with omega yields a species with a sedimentation coefficient in an alkaline medium characteristic of a covalently closed circular double-stranded DNA. Buoyant density measurements in CsCl at alkaline pH also identify the product as a covalently closed duplex ring. If the omega-catalyzed reaction is stopped short of completion, highly negatively supercoiled molecules are formed which sediment more slowly in an alkaline medium than the final duplex product. As the reaction proceeds the mean sedimentation rate of the intermediates increases. This is in agreement with the expectation that the linking number between the two complementary rings increases gradually during the course of the reaction from zero to that of a relaxed covalently closed circular DNA duplex. The possible role of DNA topoisomerases in genetic recombination is discussed.
展开
关键词：
adjustment of factors adjusted orthogonality factorial experiment nonorthogonal design pairwise orthogonality
DOI：
10.1093/nar/5.10.3811
被引量：
年份：
1978
相似文献
参考文献
引证文献
辅助模式
引用
文献可以批量引用啦~
欢迎点我试用！
