Transcriptome analysis of Pseudomonas aeruginosa PAO1 Response to Hydroxyproline

Hydroxy-L-proline (L-Hyp) mainly exists in animal collagens through post-translational modification on peptidyl proline. Utilization of L-Hyp as carbon and nitrogen sources in bacteria including P. aeruginosa requires conversion of L-Hyp to D-Hyp followed by the D-Hyp dehydrogenase pathway. However, the molecular mechanism in control of L-Hyp catabolism and transport at the genetic level was not clear. We performed a detailed transcriptome profile analysis of P. aeruginosa in response to L-Hyp and D-Hyp with an emphasis in catabolism and regulation, which revealed the presence of twelve genes in two adjacent loci that were induced by exogenous L-Hyp and D-Hyp. The first locus includes lhpABFE encoding a Hyp epimerase (LhpA) and D-Hyp dehydrogenase (LhpBEF), while the second locus covers genes for a putative ABC transporter (LhpPMNO), a protein of unknown function (LhpH), Hyp/Pro racemase (LhpK), and two enzymes in L-Hyp catabolism (LhpC and LhpG). In addition, proximal to these two loci, lhpR encodes a transcriptional regulator of the AraC family. We conducted four independent microarray experiments in the presence (experimental) of L-Hyp or D-Hyp. P. aeruginosa PAO1 was grown aerobically in minimal medium P with 300 rpm shaking at 37°C, in the presence of L-glutamate with the addition of L-Hyp or D-Hyp at 5 mM.