Analysis of Biological Activity of Escherichia coli RecQ Helicase
LUO Heng, CHEN Xiang, DUAN Li-Xia, XU Qing-He, XU Hou-Qiang
1)Guizhou Key Laboratory of Animal Genetics and Breeding Reproduction, College of Animal Sciences, Guizhou University,
Guiyang 550025, China;2) Provincial Key Laboratory for Agricultural Pest Management of Mountainous Region of Guizhou University,
Agricultural College, Guiyang 550025, China;3) Key Laboratory of Ministry of Education for Green Pesticide
and Agrobioengineering, Guizhou University, Guiyang 550025, China
Abstract：The RecQ family helicases belong to an important family of highly conserved DNA helicases that play a crucial role in the maintenance of chromosomal stability, and their mutations have been led to several disorders and cancers in human. The study is aimed to induce the expression in vitro of E. coli RecQ helicase, and to determine its biological activity using biochemical and biophysical techniques. The E. coli RecQ helicase with above 90% purity and activity was obtained in vitro, and good solubility. The E.coli RecQ helicase was shown to have DNA-binding activity, ATP-dependent DNA unwinding activity, and DNA-dependent ATPase activity. The E. coli RecQ helicase was easier to bind with single-stranded DNA (ssDNA) than double-stranded DNA (dsDNA) (P<0.01) with the difference existing in varying lengths of dsDNA(P<0.01) but not the ssDNA (P>0.05). There was a difference in DNA unwinding rate of the helicase for three lengths of dsDNA (P<0.05), and a positive correlation existed between the ATPase activity of the helicase and the length of ssDNA cofactors (P<0.01). These results are helpful to elucidate the molecular mechanisms of the E. coli RecQ helicase and study the structure and function of other members of the RecQ family helicases.
