Archaebacterial reverse gyrase cleavage-site specificity is similar to that of eubacterial DNA topoisomerases I. Nucleic Acids Res

ATP-dependent type I topoisomerases from extremely thermophllic archaebacterla- reverse gyrases- drive positive supercoiling of DNA. We showed that reverse gyrase from Desulfurococcus amylolytlcus breaks the DNA at specific sites and covalentty binds to the 5 ' end. In 30 out of 31 sites located in pBR322 DNA fragments, cleavage occurs at the sequence 5'—CNNN| — (N is any base). The same rule was previously shown to hold for single-stranded DNA breakage by eubacterial topoisomerases I. The relative cleavage frequencies at different sites depend on Mg2+ and temperature. We discuss the possible physiological and mechanistic role of the above specificity of the bacterial topoisomerases I