Transcriptome analysis of mvaT and mvaU double knockout mutant of Pseudomonas aeruginosa PAO1

MvaT and MvaU are two redundant xenogeneic silencing proteins of the H-NS family in Pseudomonas aeruginosa. Previous studies to investigate the physiological consequences of mvaT and mvaU depletion were hampered by activation of Pf4 prophage in the resulting mutants. In this study, an mvaT mvaU double knockout mutant (PAO△TU) was constructed in a strain of PAO1 (Δpf4) devoid of the Pf4 prophage on the chromosome.Transcriptome analysis by GeneChip (Affymetrix) revealed that over 227 genes were found up-regulated in PAO△TU, including several multi-gene loci for type III and type VI protein secretion systems, O-antigen, exopolysaccharide, pili assembly, and many others of unknown functions. We conducted four independent microarray experiments of phage knockout parental strain and mvaT/mvaU double knockout strain of P. aeruginosa PAO1. Strains were grown aerobically in 2YT broth with 300 rpm shaking at 37°C and harvest at mid-log phase with OD600 0.6. Comparison was made between parental strains and double knockout strains.