This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Maseda, H. Articles by Nomura, N. Search for Related Content PubMed PubMed Citation Articles by Maseda, H. Articles by Nomura, N.

 Previous Article  |  Next Article 

Antimicrobial Agents and Chemotherapy, April 2004, p. 1320-1328, Vol. 48, No. 4
0066-4804/04/$08.00+0     DOI: 10.1128/AAC.48.4.1320-1328.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

Enhancement of the mexAB-oprM Efflux Pump Expression by a Quorum-Sensing Autoinducer and Its Cancellation by a Regulator, MexT, of the mexEF-oprN Efflux Pump Operon in Pseudomonas aeruginosa

Institute of Applied Biochemistry, University of Tsukuba, Tsukuba, Ibaraki 305-8572,² Department of Molecular Life Science, Tokai University School of Medicine, Isehara, Kanagawa 259-1193, Japan¹

Received 16 May 2003/ Returned for modification 9 August 2003/ Accepted 14 December 2003

nfxC-type cells of Pseudomonas aeruginosa that produce the MexEF-OprN efflux pump exhibit resistance to fluoroquinolones and chloramphenicol and hypersusceptibility to most classical ß-lactam antibiotics. We investigated the molecular mechanism of how the nfxC mutation causes ß-lactam hypersusceptibility. The MexAB-OprM extrusion pump transports and confers resistance to ß-lactam antibiotics. Interestingly, expression of the mexAB-oprM operon reached the highest level during the mid-stationary growth phase in both wild-type and nfxC-type mutant strains, suggesting that expression of the mexAB-oprM operon may be controlled by cell density-dependent regulation such as quorum sensing. This assumption was verified by demonstrating that exogenous addition of the quorum-sensing autoinducer N-butyryl-L-homoserine lactone (C4-HSL) enhanced the expression of MexAB-OprM, whereas N-(3-oxododecanoyl)-L-homoserine lactone had only a slight effect. Furthermore, this C4-HSL-mediated enhancement of mexAB-oprM expression was repressed by MexT, a positive regulator of the mexEF-oprN operon. It was concluded that ß-lactam hypersusceptibility in nfxC-type mutant cells is caused by MexT-mediated cancellation of C4-HSL-mediated enhancement of MexAB-OprM expression.

This article has been cited by other articles:

• Yawata, Y., Nomura, N., Uchiyama, H. (2008). Development of a Novel Biofilm Continuous Culture Method for Simultaneous Assessment of Architecture and Gaseous Metabolite Production. Appl. Environ. Microbiol. 74: 5429-5435 [Abstract] [Full Text]  
• Tashiro, Y., Nomura, N., Nakao, R., Senpuku, H., Kariyama, R., Kumon, H., Kosono, S., Watanabe, H., Nakajima, T., Uchiyama, H. (2008). Opr86 Is Essential for Viability and Is a Potential Candidate for a Protective Antigen against Biofilm Formation by Pseudomonas aeruginosa. J. Bacteriol. 190: 3969-3978 [Abstract] [Full Text]  
• Stoitsova, S. O., Braun, Y., Ullrich, M. S., Weingart, H. (2008). Characterization of the RND-Type Multidrug Efflux Pump MexAB-OprM of the Plant Pathogen Pseudomonas syringae. Appl. Environ. Microbiol. 74: 3387-3393 [Abstract] [Full Text]  
• Toyofuku, M., Nomura, N., Fujii, T., Takaya, N., Maseda, H., Sawada, I., Nakajima, T., Uchiyama, H. (2007). Quorum Sensing Regulates Denitrification in Pseudomonas aeruginosa PAO1. J. Bacteriol. 189: 4969-4972 [Abstract] [Full Text]  
• Quale, J., Bratu, S., Gupta, J., Landman, D. (2006). Interplay of Efflux System, ampC, and oprD Expression in Carbapenem Resistance of Pseudomonas aeruginosa Clinical Isolates.. Antimicrob. Agents Chemother. 50: 1633-1641 [Abstract] [Full Text]  
• Chan, Y. Y., Chua, K. L. (2005). The Burkholderia pseudomallei BpeAB-OprB Efflux Pump: Expression and Impact on Quorum Sensing and Virulence. J. Bacteriol. 187: 4707-4719 [Abstract] [Full Text]  
• Palma, M., Zurita, J., Ferreras, J. A., Worgall, S., Larone, D. H., Shi, L., Campagne, F., Quadri, L. E. N. (2005). Pseudomonas aeruginosa SoxR Does Not Conform to the Archetypal Paradigm for SoxR-Dependent Regulation of the Bacterial Oxidative Stress Adaptive Response. Infect. Immun. 73: 2958-2966 [Abstract] [Full Text]  
• Aendekerk, S., Diggle, S. P., Song, Z., Hoiby, N., Cornelis, P., Williams, P., Camara, M. (2005). The MexGHI-OpmD multidrug efflux pump controls growth, antibiotic susceptibility and virulence in Pseudomonas aeruginosa via 4-quinolone-dependent cell-to-cell communication. Microbiology 151: 1113-1125 [Abstract] [Full Text]