Transcriptomic analysis of the sulfate starvation response in Pseudomonas aeruginosa

Gene expression in response to changes in sulfur supply was studied in P. aeruginosa E601, a cystic fibrosis isolate that displays mucin sulfatase activity, and in P. aeruginosa PAO1. A large family of genes was found to be upregulated by sulfate limitation in both isolates, encoding sulfatases and sulfonatases, transport systems, oxidative stress proteins, and a sulfate-regulated TonB/ExbBD complex. These genes were localized in five distinct islands on the genome, and encoded proteins with a significantly reduced content of cysteine and methionine. Growth of P. aeruginosa E601 with mucin as sulfur source led to a sulfate starvation response, but also to induction of genes involved with type III secretion systems. Keywords: starvation response, strain comparison Gene expression in exponential-phase cells was analysed using Affymetrix arrays. Sulfur was supplied either as sulfate, or as the non-sulfate S sources cyclamate (sodium cyclohexylsulfamate) and mucin (human colon cell line mucin LS174T). Control experiments were also done with combinations of these sulfur sources. Studies with mucin as sulfur source were carried out with P. aeruginosa E601 (a CF isolate with mucin sulfatase activity) and comparative studies were performed with P. aeruginosa PAO1. Experiments with strain E601 were done in 3-4 fold replication, experiments with strain PAO1 with 2-3 fold replication.