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Fluoroquinolone-Gyrase-DNA Complexes: TWO MODES OF DRUG BINDING
Journal article   Open access   Peer reviewed

Fluoroquinolone-Gyrase-DNA Complexes: TWO MODES OF DRUG BINDING

Arkady Mustaev, Muhammad Malik, Xilin Zhao, Natalia Kurepina, Gan Luan, Lisa M. Oppegard, Hiroshi Hiasa, Kevin R. Marks, Robert J. Kerns, James M. Berger, …
The Journal of biological chemistry, Vol.289(18), pp.12300-12312
02/04/2014
DOI: 10.1074/jbc.M113.529164
PMCID: PMC4007428
PMID: 24497635
url
https://doi.org/10.1074/jbc.M113.529164View
Published (Version of record) Open Access

Abstract

Background: X-ray crystal structures of fluoroquinolone-gyrase-DNA complexes reveal a single drug-binding mode. Results: A ciprofloxacin derivative with a chloroacetyl moiety at the C-7 end cross-linked with cysteine substitutions in both GyrA and GyrB that were 17 Å apart. Conclusion: Cleaved complexes containing gyrase have two fluoroquinolone-binding modes. Significance: The additional drug-binding mode provides new ways to investigate inhibitor-topoisomerase interactions. DNA gyrase and topoisomerase IV control bacterial DNA topology by breaking DNA, passing duplex DNA through the break, and then resealing the break. This process is subject to reversible corruption by fluoroquinolones, antibacterials that form drug-enzyme-DNA complexes in which the DNA is broken. The complexes, called cleaved complexes because of the presence of DNA breaks, have been crystallized and found to have the fluoroquinolone C-7 ring system facing the GyrB/ParE subunits. As expected from x-ray crystallography, a thiol-reactive, C-7-modified chloroacetyl derivative of ciprofloxacin (Cip-AcCl) formed cross-linked cleaved complexes with mutant GyrB-Cys 466 gyrase as evidenced by resistance to reversal by both EDTA and thermal treatments. Surprisingly, cross-linking was also readily seen with complexes formed by mutant GyrA-G81C gyrase, thereby revealing a novel drug-gyrase interaction not observed in crystal structures. The cross-link between fluoroquinolone and GyrA-G81C gyrase correlated with exceptional bacteriostatic activity for Cip-AcCl with a quinolone-resistant GyrA-G81C variant of Escherichia coli and its Mycobacterium smegmatis equivalent (GyrA-G89C). Cip-AcCl-mediated, irreversible inhibition of DNA replication provided further evidence for a GyrA-drug cross-link. Collectively these data establish the existence of interactions between the fluoroquinolone C-7 ring and both GyrA and GyrB. Because the GyrA-Gly 81 and GyrB-Glu 466 residues are far apart (17 Å) in the crystal structure of cleaved complexes, two modes of quinolone binding must exist. The presence of two binding modes raises the possibility that multiple quinolone-enzyme-DNA complexes can form, a discovery that opens new avenues for exploring and exploiting relationships between drug structure and activity with type II DNA topoisomerases.
Antibiotic Action Bacteria Bacterium Cleaved Complexes Cross-linking DNA and Chromosomes DNA Topoisomerase Enzyme Inhibitors Escherichia coli Mycobacterium smegmatis Resistance Mutations

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