Disease relevance of gyrB

• In this study, the quinolone resistance-determining region (QRDR) in gyrA and gyrB of in vitro fluoroquinolone-resistant Rhodococcus equi mutants was sequenced [1].
• High resistance to coumarins is produced in bacterial species by mutations in gyrB, the gene encoding subunit B. We have found an unusual mechanism of resistance to coumarins in Escherichia coli [2].
• The Bartonella bacilliformis gyrB gene, which encodes the B subunit of DNA gyrase, was cloned and sequenced [3].
• We report the cloning of the gyrB gene from Streptococcus pneumoniae 533 that carries the nov-1 allele [4].
• Detection and identification of Escherichia coli, Shigella, and Salmonella by microarrays using the gyrB gene [5].

High impact information on gyrB

• Coumermycin, a potent inhibitor of DNA gyrase subunit B, inhibits transposition in a wild-type strain, but has no effect on strains carrying a coumermycin-resistant allele in gyrB [6].
• Gene expression in a temperature-sensitive gyrB mutant of Escherichia coli [7].
• Knockout of A. thaliana gyrA is embryo-lethal whereas knockouts in the gyrB genes lead to seedling-lethal phenotypes or severely stunted growth and development [8].
• Since homologous mutant gyrB (coumermycin resistant) truncated genes did not confer drug resistance at all under the same conditions, we propose that this mechanism of resistance is due to drug sequestration by the overproduced wild-type GyrB polypeptides [2].
• We have transferred the Escherichia coli gyrA and gyrB genes onto plasmids that allow the overproduction of the DNA gyrase A and B proteins and have designed relatively simple purification procedures for both proteins [9].

Chemical compound and disease context of gyrB

• Mutations in Bartonella bacilliformis gyrB confer resistance to coumermycin A1 [3].
• Twelve quinolone-resistant clinical isolates of Escherichia coli (nalidixic acid MICs, 64 to 512 micrograms/ml; norfloxacin MICs, 0.25 to 8 micrograms/ml) were transformed with plasmid pJSW101 carrying the gyrA+ gene and with plasmid pJB11 carrying the gyrB+ gene to examine the proportion of gyrA and gyrB mutations [10].
• A novobiocin-resistant gyrB mutant Escherichia coli strain prevented expression of the runaway phenotype at 37 to 42 degrees C in the absence of any drug [11].
• Escherichia coli strain LE316 contains a mutation in gyrB that results in the substitution of Val164 to Gly and confers both chlorobiocin resistance and temperature sensitivity [12].
• An E. coli strain which carries a mutation conferring clorobiocin resistance and temperature sensitivity for growth has recently been described and evidence has been presented suggesting that the mutation is located in the gyrB gene (Orr et al. 1979) [13].

Biological context of gyrB

• The shift of a gyrB temperature-sensitive strain to the restrictive temperature is also shown to cause plasmid relaxation [14].
• Increasing temperature or relaxing supercoiled DNA resulted in a decrease in ospAB promoter activity in B. burgdorferi, but not in Escherichia coli, as well as an increase in ospC promoter activity in both bacteria. ospC promoter activity was increased in an E. coli gyrB mutant with an attenuated DNA supercoiling phenotype [15].
• By comparing the amino acid sequences, T4 39-protein is found to share homology with the gyrB subunit of DNA gyrase [16].
• Multiplexed differential gene expression analysis is demonstrated on mdh and gyrB E. coli transcripts [17].
• Effect of gyrB-mediated changes in chromosome structure on killing of Escherichia coli by ultraviolet light: experiments with strains differing in deoxyribonucleic acid repair capacity [18].

Associations of gyrB with chemical compounds

• Novobiocin resistance-conferring mutations in S. aureus, H. influenzae, and S. pneumoniae were found in gyrB, and these mutants showed little or no cross-resistance to VRT-125853 or VRT-752586 and vice versa [19].
• Previously, two independently isolated microcin B17-resistant mutants were shown to harbor the same gyrB point mutation that results in the replacement of tryptophan 751 by arginine in the GyrB polypeptide [20].
• The number of spontaneous tryptophan-independent mutations was lower in gyrB bacteria but this was almost certainly due to their poorer viability on tryptophan-limiting plates and not to a lower spontaneous mutation rate [21].
• Mutations causing aminotriazole resistance and temperature sensitivity reside in gyrB, which encodes the B subunit of DNA gyrase [22].
• After thermal inactivation of the gyrB gene product reinitiation occurs in the presence of chloramphenicol but not in the presence of rifampicin [23].

Other interactions of gyrB

• Furthermore, gyrB and parE double mutations increased the MICs of VRT-125853 and VRT-752586 significantly, providing evidence of dual targeting [19].
• In an excision-deficient (uvrA 155) background the yield of UV-induced streptomycin-resistant mutations was lower in gyrB bacteria at all doses; the yield of tryptophan-independent mutations was slightly lower at low doses and slightly higher at high doses [21].

Analytical, diagnostic and therapeutic context of gyrB

• Sequence analysis of gyrB from 12 Cour mutants of B. bacilliformis identified single nucleotide transitions at three separate loci in the ORF [3].
• Molecular cloning of the gyrA and gyrB genes of Bacteroides fragilis encoding DNA gyrase [24].
• Complementation studies with plasmid encoded cloned gyrB from Escherichia coli suggest that high fluoroquinolone resistance (minimum inhibitory concentration = 32 mg/L) in Salmonella typhimurium can be due to mutation in both gyrA and gyrB [25].
• In electrophoretic mobility shift assays, Fis was found to bind to both the gyrA and gyrB promoters of S. enterica, despite the strong divergence from the E. coli sequence on the part of the former [26].

References