Affiliation:
1. Department of Microbiology and Immunology, Queen's University, Kingston, Ontario, Canada K7L 3N6
Abstract
ABSTRACT
The MexXY components of the MexXY-OprM multidrug efflux system of
Pseudomonas aeruginosa
are encoded by a MexZ repressor-regulated operon that is inducible by antibiotics that target the ribosome. Mutant strains disrupted in a gene, PA5471, were shown to be compromised for drug-inducible
mexXY
expression and, therefore, MexXY-OprM-mediated antimicrobial resistance. The PA5471 gene was inducible by the same ribosome-targeting agents that induce
mexXY
expression. Moreover, vector-driven expression of cloned PA5471 was sufficient to promote
mexXY
expression and MexXY-mediated resistance in the absence of antibiotic exposure, consistent with PA5471 directly or indirectly activating
mexXY
expression following its own upregulation in response to antibiotics. The requirement for PA5471 for
mexXY
expression and antimicrobial resistance was, however, obviated in mutants lacking the MexZ repressor of
mexXY
expression, suggesting that PA5471 directly or indirectly modulates MexZ activity in effecting
mexXY
expression. While the recruitment of PA5471 and MexXY in response to ribosome disruption by antimicrobials is consistent with their genes playing a role in protecting cells from the adverse consequences of disrupting the translation process, reminiscent of
trans
-translation, these genes appear to operate independently in their contribution to resistance: mutants defective in
trans
-translation showed a much more modest (twofold) decrease in resistance to ribosome-targeting agents than those lacking PA5471 or MexXY, and this decrease was observed whether functional PA5471/MexXY was present or not.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
117 articles.
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