DNA gyrase, in the presence of the inhibitor oxolinic acid, can induce double-strand DNA breakage at specific sites. The sequences at several sites have been determined. In addition, the structure of complexes formed between DNA gyrase and restriction fragments containing an oxolinic acid-promoted cleavage site has been examined by DNase protection methods. DNA gyrase protects more than 120 bas...

We assign a function for a small protein, YacG encoded by Escherichia coli genome. The NMR structure of YacG shows the presence of an unusual zinc-finger motif. YacG was predicted to be a part of DNA gyrase interactome based on protein-protein interaction network. We demonstrate that YacG inhibits all the catalytic activities of DNA gyrase by preventing its DNA binding. Topoisomerase I and IV a...

Modulation of bacterial chromosomal supercoiling is a function of DNA gyrase-catalyzed strand breakage and rejoining. This reaction is exploited by both antibiotic and proteic gyrase inhibitors, which trap the gyrase molecule at the DNA cleavage stage. Owing to this interaction, double-stranded DNA breaks are introduced and replication machinery is arrested at blocked replication forks. This im...

MfpA(Mt) and QnrB4 are two newly characterized pentapeptide repeat proteins (PRPs) that interact with DNA gyrase. The mfpA(Mt) gene is chromosome borne in Mycobacterium tuberculosis, while qnrB4 is plasmid borne in enterobacteria. We expressed and purified the two PRPs and compared their effects on DNA gyrase, taking into account host specificity, i.e., the effect of MfpA(Mt) on M. tuberculosis...

DNA gyrase is the only topoisomerase able to introduce negative supercoils into DNA. Absent in humans, gyrase is a successful target for antibacterial drugs. However, increasing drug resistance is a serious problem and new agents are urgently needed. The naturally-produced Escherichia coli toxin CcdB has been shown to target gyrase by what is predicted to be a novel mechanism. CcdB has been pre...

The sugarcane pathogen Xanthomonas albilineans produces a family of antibiotics and phytotoxins termed albicidins, which inhibit plant and bacterial DNA gyrase supercoiling activity, with a 50% inhibitory concentration (50 nM) comparable to those of coumarins and quinolones. Here we show that X. albilineans has an unusual, antibiotic-resistant DNA gyrase. The X. albilineans gyrA and gyrB genes ...

DNA gyrase is an essential enzyme in DNA replication in Escherichia coli. It mediates the introduction of negative supercoils near oriC, removal of positive supercoils ahead of the growing DNA fork, and separation of the two daughter duplexes. In the course of purifying DNA gyrase from E. coli KL16, we found an 18-kDa protein that inhibited the supercoiling activity of DNA gyrase, and we coined...

OBJECTIVES Garenoxacin, a des-fluoro(6)-quinolone, exhibits potent activity against Mycoplasma pneumoniae, including macrolide-resistant strains. There has been no report on the inhibitory activity of garenoxacin against the target enzyme of M. pneumoniae. METHODS Subunits of DNA gyrase (GyrA and GyrB) proteins of M. pneumoniae FH were separately expressed as His-tagged proteins in Escherichi...

DNA gyrase is an essential type II topoisomerase found in bacteria. We have previously characterized DNA gyrase from Mycobacterium tuberculosis and Mycobacterium smegmatis. In this study, several monoclonal antibodies were generated against the gyrase A subunit (GyrA) of M. smegmatis. Three, MsGyrA:C3, MsGyrA:H11 and MsGyrA:E9, were further analyzed for their interaction with the enzyme. The mo...