Dual control of hydrogen cyanide biosynthesis by the global activator GacA in Pseudomonas aeruginosa PAO1

The global response regulator GacA of Pseudomonas aeruginosa PAO1 positively controls the production of the quorum sensing signal molecule N-butanoyl-homoserine-lactone (C4-HSL) and hence the synthesis of several C4-HSL-dependent virulence factors, including hydrogen cyanide (HCN). This study presents evidence that GacA positively influences the transcription of the rhlI gene, specifying C4-HSL synthase, explaining the quorum sensing-dependent transcriptional control of the: HCN biosynthetic genes (henABC). In addition, GacA was found to modulate hen gene expression positively at a post-transcriptional level involving the henA ribosome-binding site. Thus, the activating effect of GacA on cyanogenesis results from both transcriptional and post-transcriptional mechanisms. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.