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：1977
卷号：74
期号：12
页码：5458-5462
DOI：10.1073/pnas.74.12.5458
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The replication origin of Escherichia coli has been cloned on a nonreplicating DNA fragment coding for ampicillin resistance. This recombinant DNA, named pSY211, replicates depending on the presence of the replication origin and can be recovered as a closed circular plasmid DNA of 10.7 megadaltons (Mdal). A restriction map has been constructed. EcoRI cleaves pSY211 into two fragments: one is the ampicillin fragment of 4.5 Mdal and the other is a chromosomal fragment of 6 Mdal and contains the origin. The 6 Mdal EcoRI fragment has four BamHI sites, three HindIII sites, and one Xho I site. A mutant of pSY211 has been isolated which is lacking two BamHI fragments of the chromosomal fragment. In recA hosts, pSY211 is lost at a high frequency. In recA+ hosts, pSY211 is integrated into the chromosome due to nucleotide sequence homology between pSY211 and the replication origin of the E. coli chromosome. The integration site has been mapped. We conclude that the replication origin is located at a site between uncA and rbsK, at about 83 min on the genetic map of E. coli.
