Mutational analysis of quinolone resistance in the plasmid-encoded pentapeptide repeat proteins QnrA, QnrB and QnrS. 2009

J M Rodríguez-Martínez, and A Briales, and C Velasco, and M C Conejo, and Luis Martínez-Martínez, and A Pascual
Department of Microbiology, University of Seville, Spain. jmrodriguez@us.es

OBJECTIVE Pentapeptide repeat proteins (PRPs) QnrA, QnrB and QnrS confer reduced susceptibility to quinolones. This study presents an in vitro analysis of the genetic evolution of quinolone resistance mediated by changes in the coding sequences and promoter regions of qnrA1, qnrS1 and qnrB1 genes. METHODS A random mutagenesis technique was used to predict the evolutionary potential of these PRPs against nalidixic acid and fluoroquinolones. After comparing the amino acid sequences of these and other PRPs protecting bacteria from quinolone activity, several conserved positions were found. The role of these residues in their effect against quinolones was evaluated by site-directed mutagenesis. RESULTS Three different phenotypes (similar resistance, higher resistance or lower resistance to quinolones) were obtained in the random mutagenesis assays when compared with wild-type phenotypes. Only one mutant increased quinolone resistance: QnrS1 containing D185Y substitution (4-fold for ciprofloxacin). Using site-directed mutagenesis, residues G56, C72, C92, G96, F114, C115, S116, A117 and L159, according to the sequence of QnrA1, were analysed and despite the wide amino acid variability of the PRPs, most conserved residues analysed were critical to QnrA1, QnrB1 and QnrS1. CONCLUSIONS Amino acid sequences of PRPs QnrA1, QnrB1 and QnrS1 could be already optimized for quinolone resistance. One or several changes appear to be insufficient to obtain variants producing fluoroquinolone clinical resistance (MIC > 1 mg/L). Critical residues for quinolone resistance in PRPs were described. Interestingly, different effects were observed for QnrA1, QnrB1 and QnrS1 with the same substitution in several positions.

UI MeSH Term Description Entries
D007711 Klebsiella pneumoniae Gram-negative, non-motile, capsulated, gas-producing rods found widely in nature and associated with urinary and respiratory infections in humans. Bacillus pneumoniae,Bacterium pneumoniae crouposae,Hyalococcus pneumoniae,Klebsiella pneumoniae aerogenes,Klebsiella rhinoscleromatis
D008969 Molecular Sequence Data Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories. Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D009154 Mutation Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations. Mutations
D011401 Promoter Regions, Genetic DNA sequences which are recognized (directly or indirectly) and bound by a DNA-dependent RNA polymerase during the initiation of transcription. Highly conserved sequences within the promoter include the Pribnow box in bacteria and the TATA BOX in eukaryotes. rRNA Promoter,Early Promoters, Genetic,Late Promoters, Genetic,Middle Promoters, Genetic,Promoter Regions,Promoter, Genetic,Promotor Regions,Promotor, Genetic,Pseudopromoter, Genetic,Early Promoter, Genetic,Genetic Late Promoter,Genetic Middle Promoters,Genetic Promoter,Genetic Promoter Region,Genetic Promoter Regions,Genetic Promoters,Genetic Promotor,Genetic Promotors,Genetic Pseudopromoter,Genetic Pseudopromoters,Late Promoter, Genetic,Middle Promoter, Genetic,Promoter Region,Promoter Region, Genetic,Promoter, Genetic Early,Promoter, rRNA,Promoters, Genetic,Promoters, Genetic Middle,Promoters, rRNA,Promotor Region,Promotors, Genetic,Pseudopromoters, Genetic,Region, Genetic Promoter,Region, Promoter,Region, Promotor,Regions, Genetic Promoter,Regions, Promoter,Regions, Promotor,rRNA Promoters
D004252 DNA Mutational Analysis Biochemical identification of mutational changes in a nucleotide sequence. Mutational Analysis, DNA,Analysis, DNA Mutational,Analyses, DNA Mutational,DNA Mutational Analyses,Mutational Analyses, DNA
D004269 DNA, Bacterial Deoxyribonucleic acid that makes up the genetic material of bacteria. Bacterial DNA
D004926 Escherichia coli A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc. Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D000595 Amino Acid Sequence The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION. Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D000900 Anti-Bacterial Agents Substances that inhibit the growth or reproduction of BACTERIA. Anti-Bacterial Agent,Anti-Bacterial Compound,Anti-Mycobacterial Agent,Antibacterial Agent,Antibiotics,Antimycobacterial Agent,Bacteriocidal Agent,Bacteriocide,Anti-Bacterial Compounds,Anti-Mycobacterial Agents,Antibacterial Agents,Antibiotic,Antimycobacterial Agents,Bacteriocidal Agents,Bacteriocides,Agent, Anti-Bacterial,Agent, Anti-Mycobacterial,Agent, Antibacterial,Agent, Antimycobacterial,Agent, Bacteriocidal,Agents, Anti-Bacterial,Agents, Anti-Mycobacterial,Agents, Antibacterial,Agents, Antimycobacterial,Agents, Bacteriocidal,Anti Bacterial Agent,Anti Bacterial Agents,Anti Bacterial Compound,Anti Bacterial Compounds,Anti Mycobacterial Agent,Anti Mycobacterial Agents,Compound, Anti-Bacterial,Compounds, Anti-Bacterial
D001426 Bacterial Proteins Proteins found in any species of bacterium. Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial

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