Pritchett CL, Jones AK, Carterson AJ, Jackson D, Frisk A, Wolfgang MC, Schurr MJ.
University of Colorado Denver School of Medicine, Department of Microbiology, Aurora, CO 80045; Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599; Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, LA, 70112; Department of Biology, University of Louisiana at Monroe, LA 71209; Cystic Fibrosis/Pulmonary Research and Treatment Center, University of North Carolina, Chapel Hill, NC 27599.
Pseudomonas aeruginosa is an opportunistic pathogen that causes chronic infections in individuals suffering from the genetic disorder cystic fibrosis. In P. aeruginosa, the transcriptional regulator AlgR controls a variety of virulence factors, including alginate production, twitching motility, biofilm formation, quorum sensing and hydrogen cyanide (HCN) production. In this study, the regulation of HCN production was examined. Strains lacking AlgR or the putative AlgR sensor, AlgZ, produced significantly less HCN compared to a non-mucoid isogenic parent. In contrast, algR and algZ mutants showed increased HCN production in an alginate producing (mucoid) background. HCN production was optimal in a 5% O2 environment. In addition, cyanide production was elevated in bacteria grown on an agar surface as compared to the same bacteria grown in planktonic culture. A conserved AlgR phosphorylation site (aspartate at amino acid position 54), which is required for surface-dependent twitching motility, but not alginate production, was found to be critical for cyanide production. Nuclease protection mapping of the hcnA promoter identified a new transcriptional start site required for HCN production. A subset of clinical isolates that lack this start site produced low amounts of cyanide. Taken together, these data show that the P. aeruginosa hcnA promoter contains multiple transcriptional start sites, that HCN production is regulated by AlgZ and AlgR and maximal under microaerobic conditions when the organism is surface attached.
PMID: 19270096 [PubMed - as supplied by publisher]