The role of rpoS gene and quorum-sensing system in ofloxacin tolerance in Pseudomonas aeruginosa.
The basis of the bactericidal action of antibiotics and the mechanisms of antibiotic tolerance are largely unknown. To elucidate one of the mechanisms of antibiotic tolerance, the present study investigated the role of Pseudomonas aeruginosa quorum sensing (QS) and the rpoS gene in antibiotic tolerance. The survival rates of the lasR and lasI mutants were observed to be lower than that of the parental strain in time-dependent killing studies with 8 microg mL(-1) ofloxacin, but the survival rates of the rhlR and rhlI mutants were not different from that of the parental strain. Moreover, a lasR-overexpressing strain was more tolerant to ofloxacin than the parental strain, but this was not the case for an rhlR-overexpressing strain. The mRNA expression levels of lasR, lasI, and rpoS in the wild-type strain in the presence of bactericidal concentration of ofloxacin were lower than that in the absence of ofloxacin. In addition, the significant loss of antibiotic tolerance in the lasR mutant was recovered by the overexpression of rpoS. These results suggest that the Las QS system in P. aeruginosa is involved in the development of ofloxacin tolerance, and the tolerance induced by the Las-system is regulated by rpoS gene.
Kayama
Shizuo
S
Department of Oral Microbiology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan. kayama@dent.tokushima-u.ac.jp
Murakami
Keiji
K
Ono
Tsuneko
T
Ushimaru
Makiko
M
Yamamoto
Akitake
A
Hirota
Katsuhiko
K
Miyake
Yoichiro
Y
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D008025:Ligases / Q000235:genetics; D050296:Microbial Viability / Q000187:drug effects*; D015242:Ofloxacin / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000502:physiology*; D053038:Quorum Sensing; D012808:Sigma Factor / Q000502:physiology*; D013997:Time Factors; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C081237:LasI protein, Pseudomonas aeruginosa; C080365:LasR protein, Pseudomonas aeruginosa; C086515:RhlR protein, Pseudomonas aeruginosa; D012808:Sigma Factor; D015534:Trans-Activators; D014157:Transcription Factors; C069567:sigma factor KatF protein, Bacteria; D015242:Ofloxacin; D008025:Ligases; C096955:RHLI protein, Pseudomonas aeruginosa