FEATURES

FAMILY

type II topoisomerase GyrA/ParC subunit family

DESCRIPTION

Also known as GYRA_MYCTU, gyrA. A type II topoisomerase that negatively supercoils closed circular double-stranded (ds) DNA in an ATP-dependent manner to maintain chromosomes in an underwound state, while in the absence of ATP it relaxes supercoiled dsDNA (PubMed:15047530, PubMed:16377674, PubMed:16876125, PubMed:17015625, PubMed:18426901, PubMed:19060136, PubMed:22844097, PubMed:20805881). Also catalyzes the interconversion of other topological isomers of dsDNA rings, including catenanes (PubMed:16876125, PubMed:19060136, PubMed:22457352). Gyrase from M.tuberculosis has higher decatenation than supercoiling activity compared to E.coli; as M.tuberculosis only has 1 type II topoisomerase, gyrase has to fulfill the decatenation function of topoisomerase IV as well (PubMed:16876125, PubMed:22457352, PubMed:23869946). At comparable concentrations M.tuberculosis gyrase cannot introduce as many negative supercoils into DNA as the E.coli enzyme, and its ATPase activity is lower, perhaps because it does not couple DNA wrapping and ATP binding as well as E.coli (PubMed:22457352)., Negative supercoiling favors strand separation, and DNA replication, transcription, recombination and repair, all of which involve strand separation. Type II topoisomerases break and join 2 DNA strands simultaneously in an ATP-dependent manner. Heterotetramer, composed of two GyrA and two GyrB chains. In the heterotetramer, GyrA contains the active site tyrosine that forms a transient covalent intermediate with DNA, while GyrB binds cofactors and catalyzes ATP hydrolysis (PubMed:15047530).

EXTERNAL LINKS

gyrA

Mutations

Mutation(s) distribution

Mutations table