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：14
页码：5363-5367
DOI：10.1073/pnas.87.14.5363
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The Escherichia coli recQ gene, a member of the RecF recombination gene family, was set in an overexpression plasmid, and its product was purified to near-homogeneity. The purified RecQ protein exhibited a DNA-dependent ATPase and a helicase activity. Without DNA, no ATPase activity was detected. The capacity as ATPase cofactor varied with the type of DNA in the following order: circular single strand greater than linear single strand much greater than circular or linear duplex. As a helicase, RecQ protein displaced an annealed 71-base or 143-base single-stranded fragment from circular or linear phage M13 DNA, and the direction of unwinding seemed to be 3'----5' with respect to the DNA single strand to which the enzyme supposedly bound. Furthermore, the protein could unwind 143-base-pair blunt-ended duplex DNA at a higher enzyme concentration. It is concluded that RecQ protein is a previously unreported helicase, which might possibly serve to generate single-stranded tails for a strand transfer reaction in the process of recombination.
