Expression data from Pseudomonas aeruginosa PAO1 and its isogenic ampR mutant in the presence and absence of sub-MIC -lactam exposure.

The transcriptional regulator AmpR controls expression of the AmpC -lactamase in P. aeruginosa and other bacteria. Studies have demonstrated that in addition to regulating ampC expression, AmpR also regulates the expression of the sigma factor AlgT/U and the production of some quorum-sensing regulated virulence factors. In order to understand the ampR regulon, we compared the expression profiles of PAO1 and its isogenic ampR mutant, PAOampR in the presence and absence of sub-MIC -lactam stress. The analysis demonstrates that the ampR regulon is much more extensive than previously thought, with the deletion of ampR affecting the expression of over 300 genes. Expression of an additional 207 genes are affected by AmpR when the cells are exposed to sub-MIC -lactam stress, indicating that the ampR regulon in P. aeruginosa is much more extensive than previously thought.

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Balasubramanian D, Schneper L, Merighi M, Smith R, Narasimhan G, Lory S, Mathee K