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：1982
卷号：79
期号：24
页码：7639-7643
DOI：10.1073/pnas.79.24.7639
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：An in vitro system for replication of lambda dv plasmid DNA has been constructed. This system consists of an ammonium sulfate fraction from Escherichia coli extract, exogenously added purified lambda O and P proteins, and lambda dv DNA in closed circular form. More than 85% of the added template DNA replicated semiconservatively. In the same system, another plasmid, pBR322, also replicated, but less efficiently than lambda dv. Furthermore, its replication was independent of O and P proteins. Inhibitors of DNA gyrase entirely blocked the replication activity, whereas rifampicin, an inhibitor of RNA polymerase, showed a significant effect only when added prior to initiation of the DNA replication. DNA replication was initiated from a region near to or within the four direct repeats in lambda origin (lambda ori) and proceeded bidirectionally, as examined by DNA chain elongation termination with dideoxy CTP. A cloned DNA carrying a 350-base-pair region including the initiation site also initiated replication, dependent on O and P proteins, and its initiation occurred at the same position as with native lambda dv DNA. An A + T-rich structure neighboring the repeats was found to be essential for lambda DNA replication. Regions corresponding to ice and oop were not required for O,P-dependent initiation.
