TY - JOUR
T1 - Development of antibiotic resistance and up-regulation of the antimutator gene pfpI in mutator Pseudomonas aeruginosa due to inactivation of two DNA oxidative repair genes (mutY, mutM)
AU - Mandsberg, Lotte Frigaard
AU - Maciá, Maria D
AU - Bergmann, Kirsten R
AU - Christiansen, Lasse
AU - Alhede, Morten
AU - Kirkby, Nikolai
AU - Høiby, Niels
AU - Oliver, Antonio
AU - Ciofu, Oana
N1 - © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
PY - 2011/11
Y1 - 2011/11
N2 - Prevention and correction of oxidative DNA lesions in Pseudomonas aeruginosa is ensured by the DNA oxidative repair system (GO). Single inactivation of mutT, mutY and mutM involved in GO led to elevated mutation rates (MRs) that correlated to increased development of resistance to antibiotics. In this study, we constructed a double mutant in mutY and mutM (PAOMY-Mgm) and characterized the phenotype and the gene expression profile using microarray and RT-PCR. PAOMY-Mgm presented 28-fold increases in MR compared with wild-type reference strain PAO1. In comparison, the PAOMYgm (mutY) single mutant showed only a fivefold increase, whereas the single mutant PAOMMgm (mutM) showed a nonsignificant increase in MR compared with PAO1 and the single mutants. Mutations in the regulator nfxB leading to hyperexpression of MexCD-OprJ efflux pump were found as the mechanism of resistance to ciprofloxacin in the double mutant. A better fitness of the mutator compared with PAO1 was found in growth competition experiments in the presence of ciprofloxacin at concentrations just below minimal inhibitory concentration. Up-regulation of the antimutator gene pfpI, that has been shown to provide protection to oxidative stress, was found in PAOMY-Mgm compared with PAO1. In conclusion, we showed that MutY and MutM are cooperating in the GO of P. aeruginosa, and that oxidative DNA lesions might represent an oxidative stress for the bacteria.
AB - Prevention and correction of oxidative DNA lesions in Pseudomonas aeruginosa is ensured by the DNA oxidative repair system (GO). Single inactivation of mutT, mutY and mutM involved in GO led to elevated mutation rates (MRs) that correlated to increased development of resistance to antibiotics. In this study, we constructed a double mutant in mutY and mutM (PAOMY-Mgm) and characterized the phenotype and the gene expression profile using microarray and RT-PCR. PAOMY-Mgm presented 28-fold increases in MR compared with wild-type reference strain PAO1. In comparison, the PAOMYgm (mutY) single mutant showed only a fivefold increase, whereas the single mutant PAOMMgm (mutM) showed a nonsignificant increase in MR compared with PAO1 and the single mutants. Mutations in the regulator nfxB leading to hyperexpression of MexCD-OprJ efflux pump were found as the mechanism of resistance to ciprofloxacin in the double mutant. A better fitness of the mutator compared with PAO1 was found in growth competition experiments in the presence of ciprofloxacin at concentrations just below minimal inhibitory concentration. Up-regulation of the antimutator gene pfpI, that has been shown to provide protection to oxidative stress, was found in PAOMY-Mgm compared with PAO1. In conclusion, we showed that MutY and MutM are cooperating in the GO of P. aeruginosa, and that oxidative DNA lesions might represent an oxidative stress for the bacteria.
KW - Anti-Bacterial Agents
KW - Bacterial Proteins
KW - DNA Glycosylases
KW - DNA-Formamidopyrimidine Glycosylase
KW - Drug Resistance, Bacterial
KW - Gene Expression Profiling
KW - Gene Expression Regulation, Bacterial
KW - Gene Knockout Techniques
KW - Microarray Analysis
KW - Mutation
KW - Pseudomonas aeruginosa
KW - Reverse Transcriptase Polymerase Chain Reaction
KW - Rifampin
U2 - 10.1111/j.1574-6968.2011.02383.x
DO - 10.1111/j.1574-6968.2011.02383.x
M3 - Journal article
C2 - 22092761
SN - 0378-1097
VL - 324
SP - 28
EP - 37
JO - F E M S Microbiology Letters
JF - F E M S Microbiology Letters
IS - 1
ER -