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- Title
The role of Ca²⁺ in the activity of Mycobacterium tuberculosis DNA gyrase.
- Authors
Karkare, Shantanu; Yousafzai, Faridoon; Mitchenall, Lesley A; Maxwell, Anthony
- Abstract
DNA gyrase is the only type II topoisomerase in Mycobacterium tuberculosis and needs to catalyse DNA supercoiling, relaxation and decatenation reactions in order to fulfil the functions normally carried out by gyrase and DNA topoisomerase IV in other bacteria. We have obtained evidence for the existence of a Ca(2+)-binding site in the GyrA subunit of M. tuberculosis gyrase. Ca(2+) cannot support topoisomerase reactions in the absence of Mg(2+), but partial removal of Ca(2+) from GyrA by dialysis against EGTA leads to a modest loss in relaxation activity that can be restored by adding back Ca(2+). More extensive removal of Ca(2+) by denaturation of GyrA and dialysis against EGTA results in an enzyme with greatly reduced enzyme activities. Mutation of the proposed Ca(2+)-binding residues also leads to loss of activity. We propose that Ca(2+) has a regulatory role in M. tuberculosis gyrase and suggest a model for the modulation of gyrase activity by Ca(2+) binding.
- Publication
Nucleic acids research, 2012, Vol 40, Issue 19, p9774
- ISSN
1362-4962
- Publication type
Journal Article
- DOI
10.1093/nar/gks704