HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Cooper, M. Articles by Williams, H. D. Search for Related Content PubMed PubMed Citation Articles by Cooper, M. Articles by Williams, H. D. Agricola Articles by Cooper, M. Articles by Williams, H. D.

Regulation of expression of the cyanide-insensitive terminal oxidase in Pseudomonas aeruginosa

Megan Cooper

Department of Biological Sciences, Imperial College London, Sir Alexander Fleming Building, South Kensington Campus, London SW7 2AZ, UK

Correspondence
Huw D. Williams
h.d.williams{at}imperial.ac.uk

The regulation of the cyanide-insensitive oxidase (CIO) in Pseudomonas aeruginosa, a bacterium that can synthesize HCN, is reported. The expression of a cioA–lacZ transcriptional fusion, CioA protein levels and CIO activity were low in exponential phase but induced about fivefold upon entry into stationary phase. Varying the O₂ transfer coefficient from 11·5 h^-1 to 87·4 h^-1 had no effect on CIO expression and no correlation was observed between CIO induction and the dissolved O₂ levels in the growth medium. However, a mutant deleted for the O₂-sensitive transcriptional regulator ANR derepressed CIO expression in an O₂-sensitive manner, with the highest induction occurring under low-O₂ conditions. Therefore, CIO expression can respond to a signal generated by low O₂ levels, but this response is normally kept in check by ANR repression. ANR may play an important role in preventing overexpression of the CIO in relation to other terminal oxidases. A component present in spent culture medium was able to induce CIO expression. However, experiments with purified N-butanoyl-L-homoserine lactone or N-(3-oxododecanoyl)homoserine lactone ruled out a role for these quorum-sensing molecules in the control of CIO expression. Cyanide was a potent inducer of the CIO at physiologically relevant concentrations and experiments using spent culture medium from a hcnB mutant, which is unable to synthesize cyanide, showed that cyanide was the inducing factor present in P. aeruginosa spent culture medium. However, the finding that in a hcnB mutant cioA–lacZ expression was induced normally upon entry into stationary phase indicated that cyanide was not the endogenous inducer of the terminal oxidase. The authors suggest that the failure of O₂ to have an effect on CIO expression in the wild-type can be explained either by the requirement for an additional, stationary-phase-specific inducing signal or by the loss of an exponential-phase-specific repressing signal.

Present address: Defence Science and Technology Laboratories, Fort Halstead, Sevenoaks, Kent TN14 7BP, UK.

This article has been cited by other articles:

				R. J. Jackson, K. T. Elvers, L. J. Lee, M. D. Gidley, L. M. Wainwright, J. Lightfoot, S. F. Park, and R. K. Poole Oxygen Reactivity of Both Respiratory Oxidases in Campylobacter jejuni: the cydAB Genes Encode a Cyanide-Resistant, Low-Affinity Oxidase That Is Not of the Cytochrome bd Type J. Bacteriol., March 1, 2007; 189(5): 1604 - 1615. [Abstract] [Full Text] [PDF]

				R. Cipollone, E. Frangipani, F. Tiburzi, F. Imperi, P. Ascenzi, and P. Visca Involvement of Pseudomonas aeruginosa Rhodanese in Protection from Cyanide Toxicity Appl. Envir. Microbiol., January 1, 2007; 73(2): 390 - 398. [Abstract] [Full Text] [PDF]

				N. Boes, K. Schreiber, E. Hartig, L. Jaensch, and M. Schobert The Pseudomonas aeruginosa Universal Stress Protein PA4352 Is Essential for Surviving Anaerobic Energy Stress. J. Bacteriol., September 1, 2006; 188(18): 6529 - 6538. [Abstract] [Full Text] [PDF]

				J. E. A. Zlosnik, G. R. Tavankar, J. G. Bundy, D. Mossialos, R. O'Toole, and H. D. Williams Investigation of the physiological relationship between the cyanide-insensitive oxidase and cyanide production in Pseudomonas aeruginosa. Microbiology, May 1, 2006; 152(Pt 5): 1407 - 1415. [Abstract] [Full Text] [PDF]

				J. M. Gaines, N. L. Carty, J. A. Colmer-Hamood, and A. N. Hamood Effect of static growth and different levels of environmental oxygen on toxA and ptxR expression in the Pseudomonas aeruginosa strain PAO1 Microbiology, July 1, 2005; 151(7): 2263 - 2275. [Abstract] [Full Text] [PDF]