Analysis of Biological Activity of Escherichia coli RecQ Helicase

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-strandedDNA(ssDNA)than double-stranded DNA(dsDNA)(P0.01)with the difference existing in varyinglengths of dsDNA(P0.01)but not the ssDNA(P0.05).There was a difference in DNA unwindingrate of the helicase for three lengths of dsDNA(P0.05),and a positive correlation existed between theATPase activity of the helicase and the length of ssDNA cofactors(P0.01).These results are helpfulto elucidate the molecular mechanisms of the E.coli RecQ helicase and study the structure and functionof other members of the RecQ family helicases.