title: Intrinsic DNA-dependent ATPase activity of reverse gyrase.
abstract: Reverse gyrase is a type I DNA topoisomerase that promotes positive supercoiling of closed-circular double-stranded DNA through an ATP-dependent reaction, and it was purified from an archaebacterium, Sulfolobus. When ATP is replaced by UTP, GTP, or CTP, this enzyme just relaxes the negatively supercoiled closed-circular double-stranded DNA. We found that reverse gyrase hydrolyzes ATP through a double-stranded DNA-dependent reaction. The superhelicity of the DNA did not affect the ATPase activity. However, reverse gyrase does not hydrolyze UTP, GTP, or CTP. Therefore, any of the four nucleotide 5'-triphosphates acts as an effector for the topoisomerase activity of reverse gyrase, but only ATP supports the positive supercoiling of closed-circular double-stranded DNA, through the energy released on its hydrolysis. Single-stranded DNA was a much more potent cofactor for the ATPase activity of the enzyme than double-stranded DNA, and it acted as a potent inhibitor for the topoisomerase activity on double-stranded DNA. These results indicate that reverse gyrase has higher affinity to single-stranded DNA than to double-stranded DNA, which suggests a cellular function of the enzyme.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D001105:Archaea / Q000201:enzymology; D003570:Cytidine Triphosphate / Q000378:metabolism; D004247:DNA / Q000494:pharmacology*; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004278:DNA, Superhelical / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D013379:Substrate Specificity; D014544:Uridine Triphosphate / Q000378:metabolism
chemical_list: D004277:DNA, Single-Stranded; D004278:DNA, Superhelical; D003570:Cytidine Triphosphate; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D004247:DNA; D000251:Adenosine Triphosphatases; C041813:DNA reverse gyrase; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II; D014544:Uridine Triphosphate