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：1990
卷号：87
期号：7
页码：2481-2485
DOI：10.1073/pnas.87.7.2481
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A polar DNA replication barrier is formed when the DNA-binding protein Tus forms a complex with any of the four 23-base-pair terminator (ter) sites found in the terminus region of the Escherichia coli chromosome. We have used a plasmid DNA replication system reconstituted with purified proteins in vitro to investigate the interaction of the Tus protein with the replication fork. Purified Tus protein alone is necessary and sufficient to arrest DNA replication on ColE1-type plasmid templates containing ter sites. Tus protein-catalyzed termination depends upon the orientation of the ter site in the plasmid DNA. Nucleotide resolution mapping of the terminated nascent DNA shows that leading-strand DNA synthesis arrests at the point of contact with the Tus protein, while the final lagging-strand primer sites are 50-70 nucleotides upstream. In addition, the distribution of leading-strand arrest sites changes when the composition of the proteins on the lagging-strand side of the replication fork is altered.
