Format

Send to

Choose Destination
Proc Natl Acad Sci U S A. 1996 Dec 10;93(25):14416-21.

Conversion of DNA gyrase into a conventional type II topoisomerase.

Author information

1
Department of Biochemistry, University of Leicester, United Kingdom.

Abstract

DNA gyrase is unique among topoisomerases in its ability to introduce negative supercoils into closed-circular DNA. We have demonstrated that deletion of the C-terminal DNA-binding domain of the A subunit of gyrase gives rise to an enzyme that cannot supercoil DNA but relaxes DNA in an ATP-dependent manner. Novobiocin, a competitive inhibitor of ATP binding by gyrase, inhibits this reaction. The truncated enzyme, unlike gyrase, does not introduce a right-handed wrap when bound to DNA and stabilizes DNA crossovers; characteristics reminiscent of conventional type II topoisomerases. This new enzyme form can decatenate DNA circles with increased efficiency compared with intact gyrase and, as a result, can complement the temperature-sensitive phenotype of a parCts mutant. Thus these results suggest that the unique properties of DNA gyrase are attributable to the wrapping of DNA around the C-terminal DNA-binding domains of the A subunits and provide an insight into the mechanism of type II topoisomerases.

PMID:
8962066
PMCID:
PMC26147
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center