Characterization of Campylobacter jejuni DNA gyrase as the target of quinolones.

Abstract

Quinolones have long been used as the first-line treatment for Campylobacter infections. However, an increased resistance to quinolones has raised public health concerns. The development of new quinolone-based antibiotics with high activity is critical for effective, as DNA gyrase, the target of quinolones, is an essential enzyme for bacterial growth in several mechanisms. The evaluation of antibiotic activity against Campylobacter jejuni largely relies on drug susceptibility tests, which require at least 2 days to produce results. Thus, an in vitro method for studying the activity of quinolones against the C. jejuni DNA gyrase is preferred. To identify potent quinolones, we investigated the interaction of C. jejuni DNA gyrase with a number of quinolones using recombinant subunits. The combination of purified subunits exhibited DNA supercoiling activity in an ATP dependent manner. Drug concentrations that inhibit DNA supercoiling by 50% (IC50s) of 10 different quinolones were estimated to range from 0.4 (sitafloxacin) to >100 μg/mL (nalidixic acid). Sitafloxacin showed the highest inhibitory activity, and the analysis of the quinolone structure-activity relationship demonstrated that a fluorine atom at R-6 might play the important role in the inhibitory activity against C. jejuni gyrase. Measured quinolone IC50s correlated well with minimum inhibitory concentrations (R = 0.9943). These suggest that the in vitro supercoiling inhibition assay on purified recombinant C. jejuni DNA gyrase is a useful and predictive technique to monitor the antibacterial potency of quinolones. And furthermore, these data suggested that sitafloxacin might be a good candidate for clinical trials on campylobacteriosis.

• Authors: Ruchirada Changkwanyeun, Masaru Usui, Siriporn Kongsoi, Kazumasa Yokoyama, Hyun Kim, Orasa Suthienkul, Kanjana Changkaew, Chie Nakajima, Yutaka Tamura, Yasuhiko Suzuki
• Journal: Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy (J Infect Chemother) Vol. 21 Issue 8 Pg. 604-9 (Aug 2015) ISSN: 1437-7780 [Electronic] Netherlands
• PMID: 26096494 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2015 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Chemical References

• Anti-Bacterial Agents
• DNA, Bacterial
• Fluoroquinolones
• Quinolones
• Recombinant Proteins
• Topoisomerase II Inhibitors
• sitafloxacin
• DNA Gyrase

Topics

• Anti-Bacterial Agents (chemistry, pharmacology)
• Campylobacter jejuni (drug effects, enzymology, genetics)
• DNA Gyrase (genetics)
• DNA, Bacterial (chemistry)
• Fluoroquinolones (chemistry, pharmacology)
• Inhibitory Concentration 50
• Microbial Sensitivity Tests (methods)
• Molecular Conformation (drug effects)
• Quinolones (chemistry, pharmacology)
• Recombinant Proteins (chemistry)
• Structure-Activity Relationship
• Topoisomerase II Inhibitors (pharmacology)