GeneChip Expression Analysis of the Response of Pseudomonas aeruginosa to Paraquat-Induced Superoxide Stress

Abstract

The genome-wide transcription profile against the superoxide-generating agent paraquat was measured in the Pseudomonas aeruginosa reference strain PAO1 and the cystic fibrosis isolates TB (TBCF10839) and 892 (TBCF127838) with the use of the Affymetrix GeneChip P. aeruginosa PAO1 genome array representing 5900 P. aeruginosa coding sequences. A total of 24, 27, and 29 genes was found to be significantly differentially expressed in strains TB, 892, and PAO1 in the presence of paraquat, of which only six genes were consistently up-regulated in all three strains. mRNA transcripts belonging to the categories of transport, oxidative stress response, or acetyl-CoA and acetoin metabolism were strain-specifically induced by 2–17-fold (mean [SD] 3.9 [2.8]), whereas mRNA transcripts of elements of the oxidative energy metabolism were repressed by 2–7-fold (mean [SD] 3.6 [1.1]). One operon encoding four proteins of previously unknown function (PA0939-PA0942) was 20–200-fold up-regulated in all three analyzed strains. This operon that exhibits the strongest up-regulation and the constitutively highly expressed manganese-dependent superoxide dismutase SodB, the catalase KatA, and the alkylhydroperoxide reductase AhpC seem to confer the most resistance to paraquat-induced stress in P. aeruginosa.