Molecular cloning of the DNA gyrase genes from Methylovorus sp. strain SS1 and the mechanism of intrinsic quinolone resistance in methylotrophic bacteria.
The genes encoding the DNA gyrase A (GyrA) and B subunits (GyrB) of Methylovorus sp. strain SS1 were cloned and sequenced. gyrA and gyrB coded for proteins of 846 and 799 amino acids with calculated molecular weights of 94,328 and 88,714, respectively, and complemented Escherichia coli gyrA and gyrB temperature sensitive (ts) mutants. To analyze the role of type II topoisomerases in the intrinsic quinolone resistance of methylotrophic bacteria, the sequences of the quinolone resistance-determining regions (QRDRs) in the A subunit of DNA gyrase and the C subunit (ParC) of topoisomerase IV (Topo IV) of Methylovorus sp. strain SS1, Methylobacterium extorquens AM1 NCIB 9133, Methylobacillus sp, strain SK1 DSM 8269, and Methylophilus methylotrophus NCIB 10515 were determined. The deduced amino acid sequences of the QRDRs of the ParCs in the four methylotrophic bacteria were identical to that of E. coli ParC. The sequences of the QRDR in GyrA were also identical to those in E. coli GyrA except for the amino acids at positions 83, 87, or 95. The Ser83 to Thr substitution in Methylovorus sp. strain SS1, and the Ser83 to Leu and Asp87 to Asn substitutions in the three other methylotrophs, agreed well with the minimal inhibitory concentrations of quinolones in the four bacteria, suggesting that these residues play a role in the intrinsic susceptibility of methylotrophic bacteria to quinolones.
Kim
Kwang-Seo
KS
Molecular Microbiology Laboratory, Department of Biology, Yonsei University, Seoul 120-749, Korea.
Kim
Jeong Hoon
JH
Kim
Do Yeob
DY
Kim
Hyun Jong
HJ
Park
Sang Tae
ST
Kim
Young Min
YM
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001483:Base Sequence; D003001:Cloning, Molecular; D027081:DNA Gyrase / Q000235:genetics* / Q000378:metabolism; D027101:DNA Topoisomerase IV / Q000235:genetics; D004269:DNA, Bacterial; D024881:Drug Resistance, Bacterial; D024841:Fluoroquinolones / Q000494:pharmacology*; D005798:Genes, Bacterial; D020580:Methylobacterium / Q000187:drug effects* / Q000201:enzymology; D042762:Methylophilaceae / Q000737:chemistry / Q000235:genetics; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation
D004269:DNA, Bacterial; D024841:Fluoroquinolones; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase