Recognition of DNA Supercoil Geometry by Mycobacterium tuberculosis Gyrase

Ashley, R.E.; Blower, T.R.; Berger, J.M.; Osheroff, N.

Abstract

Mycobacterium tuberculosis encodes only a single type II topoisomerase, gyrase. As a result, this enzyme likely carries out the cellular functions normally performed by canonical gyrase and topoisomerase IV, both in front of and behind the replication fork. In addition, it is the sole target for quinolone antibacterials in this species. Because quinolone-induced DNA strand breaks generated on positively supercoiled DNA ahead of replication forks and transcription complexes are most likely to result in permanent genomic damage, the actions of M. tuberculosis gyrase on positively supercoiled DNA were investigated. Results indicate that the enzyme acts rapidly on overwound DNA and removes positive supercoils much faster than it introduces negative supercoils into relaxed DNA. Canonical gyrase and topoisomerase IV distinguish supercoil handedness differently during the DNA cleavage reaction: while gyrase maintains lower levels of cleavage complexes on overwound DNA, topoisomerase IV maintains similar levels of cleavage complexes on both over- and underwound substrates. M. tuberculosis gyrase maintained lower levels of cleavage complexes on positively supercoiled DNA in the absence and presence of quinolone-based drugs. By retaining this important feature of canonical gyrase, the dual function M. tuberculosis type II enzyme remains a safe enzyme to act in front of replication forks and transcription complexes. Finally, the N-terminal gate region of the enzyme appears to be necessary to distinguish supercoil handedness during DNA cleavage, suggesting that the capture of the transport segment may influence how gyrase maintains cleavage complexes on substrates with different topological states.

Citation

Ashley, R., Blower, T., Berger, J., & Osheroff, N. (2017). Recognition of DNA Supercoil Geometry by Mycobacterium tuberculosis Gyrase. Biochemistry, 56(40), 5440-5448. https://doi.org/10.1021/acs.biochem.7b00681

• Journal Article Type: Article
• Acceptance Date: Sep 18, 2017
• Online Publication Date: Sep 18, 2017
• Publication Date: Oct 10, 2017
• Deposit Date: Sep 21, 2017
• Publicly Available Date: Sep 18, 2018
• Journal: Biochemistry.
• Print ISSN: 0006-2960
• Electronic ISSN: 1520-4995
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 56
• Issue: 40
• Pages: 5440-5448
• DOI: https://doi.org/10.1021/acs.biochem.7b00681
• Public URL: https://durham-repository.worktribe.com/output/1348851