Characterization of the SOS response of Pseudomonas fluorescens strain DC454 using whole genome transcript analysis

DNA microarray technology was used to survey changes in gene expression in P. fluorescens after mitomycin C (MMC) treatment. As expected, genes associated with the SOS response were upregulated. These include genes coding the recombination involved protein RecA, DNA repair protein RecN, excinuclease ABC subunit A UvrA, and the LexA repressor protein. The expression profile was similar to that which had been shown for E. coli after MMC treatment. Interestingly, expression of 33 bacteriophage-like genes was upregulated two hours after MMC treatment. Those genes are clustered in the chromosome. This result suggests that MMC may induce a prophage resident in the P. fluorescens genome. However, no phage particles were detected in a preparation of P. fluorescens strain DC454 that had been treated with MMC using transmission electron microscopy, and the same preparation failed to produce phage plaques on lawns of any of 10 different Pseudomonas strains tested, suggesting that the 33 bacteriophage-like gene cluster represents a defective prophage. Keywords: time course, stress response These are the time points comparisons for 1hs vs 0hs and 2 hr vs 0 hr. The same comparisons were performed for the control strain and MMC treated strain. Dye swaps were included for each comparison. Therefore, there are 8 pairs in total.