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DNA Topoisomerase inhibitors: trapping a DNA-cleaving machine in motion

Bax, Benjamin D., Murshudov, Garib, Maxwell, Anthony and Germe, Thomas 2019. DNA Topoisomerase inhibitors: trapping a DNA-cleaving machine in motion. Journal of Molecular Biology 431 (18) , pp. 3427-3449. 10.1016/j.jmb.2019.07.008

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Abstract

Type II topoisomerases regulate DNA topology by making a double-stranded break in one DNA duplex, transporting another DNA segment through this break and then resealing it. Bacterial type IIA topoisomerase inhibitors, such as fluoroquinolones and novel bacterial topoisomerase inhibitors, can trap DNA cleavage complexes with double- or single-stranded cleaved DNA. To study the mode of action of such compounds, 21 crystal structures of a “gyraseCORE” fusion truncate of Staphyloccocus aureus DNA gyrase complexed with DNA and diverse inhibitors have been published, as well as 4 structures lacking inhibitors. These structures have the DNA in various cleavage states and appear to track trajectories along the catalytic paths of the DNA cleavage/religation steps. The various conformations sampled by these multiple “gyraseCORE” structures show rigid body movements of the catalytic GyrA WHD and GyrB TOPRIM domains across the dimer interface. Conformational changes common to all compound-bound structures suggest common mechanisms for DNA cleavage-stabilizing compounds. The structures suggest that S. aureus gyrase uses a single moving-metal ion for cleavage and that the central four base pairs need to be stretched between the two catalytic sites, in order for a scissile phosphate to attract a metal ion to the A-site to catalyze cleavage, after which it is “stored” in another coordination configuration (B-site) in the vicinity. We present a simplified model for the catalytic cycle in which capture of the transported DNA segment causes conformational changes in the ATPase domain that push the DNA gate open, resulting in stretching and cleaving the gate-DNA in two steps.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Biosciences
Publisher: Elsevier
ISSN: 0022-2836
Date of First Compliant Deposit: 29 July 2019
Date of Acceptance: 2 July 2019
Last Modified: 11 Sep 2019 02:05
URI: http://orca.cardiff.ac.uk/id/eprint/124534

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