title: 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.affiliation: Division of Bioresources, Hokkaido University Research Center for Zoonosis Control, Sapporo, Japan.
authors.forename: Ruchirada
authors.initials: R
authors.lastname: Changkwanyeun
authors.affiliation: Laboratory of Food Microbiology and Food Safety, Department of Health and Environmental Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Usui
authors.affiliation: Division of Bioresources, Hokkaido University Research Center for Zoonosis Control, Sapporo, Japan.
authors.forename: Siriporn
authors.initials: S
authors.lastname: Kongsoi
authors.affiliation: Central Research Laboratory, Kissei Pharmaceutical Co., Ltd, Azumino, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Yokoyama
authors.affiliation: Laboratory of Tuberculosis Control, Department of Bacteriology II, National Institute of Infectious Diseases, Musashi Murayama, Japan.
authors.forename: Hyun
authors.initials: H
authors.lastname: Kim
authors.affiliation: Faculty of Public Health, Thammasat University, Rangsit, Thailand; Department of Microbiology, Faculty of Public Health, Mahidol University, Bangkok, Thailand.
authors.forename: Orasa
authors.initials: O
authors.lastname: Suthienkul
authors.affiliation: Division of Bioresources, Hokkaido University Research Center for Zoonosis Control, Sapporo, Japan.
authors.forename: Kanjana
authors.initials: K
authors.lastname: Changkaew
authors.affiliation: Division of Bioresources, Hokkaido University Research Center for Zoonosis Control, Sapporo, Japan; Hokkaido University, The Global Station for Zoonosis Control, Sapporo, Japan.
authors.forename: Chie
authors.initials: C
authors.lastname: Nakajima
authors.affiliation: Laboratory of Food Microbiology and Food Safety, Department of Health and Environmental Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Tamura
authors.affiliation: Division of Bioresources, Hokkaido University Research Center for Zoonosis Control, Sapporo, Japan; Hokkaido University, The Global Station for Zoonosis Control, Sapporo, Japan. Electronic address: suzuki@czc.hokudai.ac.jp.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Suzuki
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology; D016123:Campylobacter jejuni / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D027081:DNA Gyrase / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry*; D024841:Fluoroquinolones / Q000737:chemistry / Q000494:pharmacology; D020128:Inhibitory Concentration 50; D008826:Microbial Sensitivity Tests / Q000379:methods*; D008968:Molecular Conformation / Q000187:drug effects; D015363:Quinolones / Q000737:chemistry / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000737:chemistry; D013329:Structure-Activity Relationship; D059005:Topoisomerase II Inhibitors / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D024841:Fluoroquinolones; D015363:Quinolones; D011994:Recombinant Proteins; D059005:Topoisomerase II Inhibitors; C076246:sitafloxacin; D027081:DNA Gyrase
keywords: Campylobacter jejuni; DNA gyrase; Quinolones