Comparing the transcriptional profiles of a Caulobacter crescentus phyR null mutant to a xylose-inducible phyR overexpression strain. Caulobacter vibrioides

phyR encodes a general stress regulator protein that is conserved among several alpha-proteobacteria. This experiment is quantifying transcription in two Caulobacter strains: one strain is overexpressing phyR (gene CC3477); the other carries a phyR in-frame deletion. Both strains were cultured in M2 defined medium with xylose as the sole carbon source. The first strain (FC626) carries a plasmid integrated into the xylX locus; phyR is fused to the xylX promoter in this plasmid, generating a xylose-inducible phyR overexpression strain. The second strain (FC799) carries an in-frame deletion at the chromosomal phyR locus. Overall design: Duplicate cultures of: 1) C. crescentus strain CB15 phyR in-frame deletion mutant , and 2) a xylose-inducible phyR overexpression strain, were cultured in M2 xylose defined medium and harvested at OD660=0.3