The DNA-gate of Bacillus subtilis gyrase is predominantly in the closed conformation during the DNA supercoiling reaction
- 11 August 2009
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 106 (32), 13278-13283
- https://doi.org/10.1073/pnas.0902493106
Abstract
Gyrase is the only type II topoisomerase that introduces negative supercoils into DNA. Supercoiling is catalyzed via a strand-passage mechanism, in which the gate DNA (gDNA) is transiently cleaved, and a second DNA segment, the transfer DNA (tDNA), is passed through the gap before the gDNA is religated. Strand passage requires an opening of the so-called DNA-gate by approximately 2 nm. A single-molecule FRET study reported equal populations of open and closed DNA-gate in topoisomerase II. We present here single-molecule FRET experiments that monitor the conformation of DNA bound to the DNA-gate of Bacillus subtilis gyrase and the conformation of the DNA-gate itself. DNA bound to gyrase adopts two different conformations, one slightly, one severely distorted. DNA distortion requires cleavage, but neither ATP nor the presence of a tDNA. At the same time, the DNA-gate of gyrase is predominantly in the closed conformation. In agreement with the single molecule data and with the danger of dsDNA breaks for genome integrity, <5% of cleavage complexes are detected in equilibrium. Quinolone inhibitors favor DNA cleavage by B. subtilis gyrase, but disfavor DNA distortion, and the DNA-gate remains in the closed conformation. Our results demonstrate that DNA binding, distortion and cleavage, and gate-opening are mechanistically distinct events. During the relaxation and supercoiling reactions, gyrase with an open DNA-gate is not significantly populated, consistent with gate-opening as a very rare event that only occurs briefly to allow for strand passage.Keywords
This publication has 47 references indexed in Scilit:
- Analysis of the eukaryotic topoisomerase II DNA gate: a single-molecule FRET and structural perspectiveNucleic Acids Research, 2009
- Topoisomerase II: a fitted mechanism for the chromatin landscapeNucleic Acids Research, 2008
- Coupling between ATP Binding and DNA Cleavage by DNA Topoisomerase IIPublished by Elsevier BV ,2008
- Using 3′-Bridging Phosphorothiolates To Isolate the Forward DNA Cleavage Reaction of Human Topoisomerase IIαBiochemistry, 2008
- Cooperative binding of ATP and RNA induces a closed conformation in a DEAD box RNA helicaseProceedings of the National Academy of Sciences of the United States of America, 2008
- DNA topoisomerase II selects DNA cleavage sites based on reactivity rather than binding affinityNucleic Acids Research, 2007
- Breakage-Reunion Domain of Streptococcus pneumoniae Topoisomerase IV: Crystal Structure of a Gram-Positive Quinolone TargetPLOS ONE, 2007
- Unlocking and opening a DNA gateProceedings of the National Academy of Sciences of the United States of America, 2007
- Single-molecule measurements of the opening and closing of the DNA gate by eukaryotic topoisomerase IIProceedings of the National Academy of Sciences of the United States of America, 2007
- Locking the ATP-operated clamp of DNA gyrase: probing the mechanism of strand passageJournal of Molecular Biology, 2001