Vibrio parahaemolyticus causes seafood-borne gastroenteritis in humans. It is particularly important in Japan, where raw seafood is frequently consumed. Fluoroquinolone is one of the current drugs of choice for treating patients infected by V. parahaemolyticus because resistant strains are rarely found. To study a possible fluoroquinolone resistance mechanism in this organism, nucleotide sequen...

DNA gyrase is the only topoisomerase capable of introducing (-) supercoils into relaxed DNA. The C-terminal domain of the gyrase A subunit (GyrA-CTD) and the presence of a gyrase-specific 'GyrA-box' motif within this domain are essential for this unique (-) supercoiling activity by allowing gyrase to wrap DNA around itself. Here we report the crystal structure of Xanthomonas campestris GyrA-CTD...

Quinolones are a large and widely consumed class of synthetic drugs. Expanded-spectrum quinolones, like ciprofloxacin are highly effective against Gram-negative bacteria, especially Escherichia coli. In E. coli the major target for quinolones is DNA gyrase. This enzyme is composed of two subunits, GyrA and GyrB encoding by gyrA and gyrB, respectively. Mutations in either of these genes cause qu...

   Ciprofloxacin is one of the most widely used antibiotics for the treatment of several infections caused by Gram-negative bacteria, like E. coli. Changes in gyrA, encoding GyrA subunit of DNA gyrase, cause the resistance to ciprofloxacin. Some ciprofloxacin resistant gyrA mutants acquired constitutive expression of marRAB operon due to the gaining mutations in marR, a repressor of this operon...

The sequence of the DNA gyrase gyrA gene of Serratia marcescens ATCC 14756 was determined. An open reading frame of 2,640 nucleotides coding for a polypeptide with a calculated molecular mass of 97,460 was found, and its sequence complemented the sequence of an Escherichia coli gyrA temperature-sensitive mutation. Analysis of the PCR products of the quinolone resistance-determining regions of g...

In contrast with most bacteria which possess two type II topoisomerases (topoisomerase IV and DNA gyrase), Mycobacterium tuberculosis possesses only one, DNA gyrase, which is functionally a hybrid enzyme. Functional differences between the two type IIA topoisomerases are thought to be specified by a CTD (C-terminal DNA-binding domain), which controls DNA recognition. To explore the molecular me...

Two different type II topoisomerases are known in bacteria. DNA gyrase (Gyr) introduces negative supercoils into DNA. Topoisomerase IV (Par) relaxes DNA supercoils. GyrA and ParC subunits of bacterial type II topoisomerases are involved in breakage and reunion of DNA. The spatial structure of the C-terminal fragment in GyrA/ ParC is not available. We infer homology between the C-terminal domain...

The proportion of DNA gyrase mutants among quinolone-resistant strains of Pseudomonas aeruginosa was examined by introducing the cloned wild-type Escherichia coli gyrA and gyrB genes. Of 101 spontaneous mutants of P. aeruginosa PAO505, 33 (33%) were found to have gyrA mutations. Among 17 clinical isolates, 12 (71%) had gyrA mutations and 1 (6%) had a gyrB mutation.

The quinolones exert their anti-bacterial activity by binding to DNA gyrase A (GyrA), an essential enzyme in maintenance of DNA topology within bacterial cell. The mutations conferring resistance to quinolones arise within the quinolone-resistance-determining region (QRDR) of GyrA. Therefore, quinolones interaction with wild and mutated GyrA can provide the molecular explanation for resistance....

Oxolinic acid (OA), a quinolone, inhibits the activity of DNA gyrase composed of GyrA and GyrB and shows antibacterial activity against Burkholderia glumae. Since B. glumae causes bacterial seedling rot and grain rot of rice, both of which are devastating diseases, the emergence of OA-resistant bacteria has important implications on rice cultivation in Japan. Based on the MIC of OA, 35 B. gluma...