This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lamb, J. R. Articles by Iglewski, B. H. Search for Related Content PubMed PubMed Citation Articles by Lamb, J. R. Articles by Iglewski, B. H.

 Previous Article  |  Next Article 

Journal of Bacteriology, December 2003, p. 7129-7139, Vol. 185, No. 24
0021-9193/03/$08.00+0     DOI: 10.1128/JB.185.24.7129-7139.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

Functional Domains of the RhlR Transcriptional Regulator of Pseudomonas aeruginosa

University of Rochester, Rochester, New York 14642

Received 12 May 2003/ Accepted 15 September 2003

The RhlR transcriptional regulator of Pseudomonas aeruginosa, along with its cognate autoinducer, N-butyryl homoserine lactone (C₄-HSL), regulates gene expression in response to cell density. With an Escherichia coli LexA-based protein interaction system, we demonstrated that RhlR multimerized and that the degree of multimerization was dependent on the C₄-HSL concentration. Studies with an E. coli lasB::lacZ lysogen demonstrated that RhlR multimerization was necessary for it to function as a transcriptional activator. Deletion analysis of RhlR indicated that the N-terminal domain of the protein is necessary for C₄-HSL binding. Single amino acid substitutions in the C-terminal domain of RhlR generated mutant RhlR proteins that had the ability to bind C₄-HSL and multimerize but were unable to activate lasB expression, demonstrating that the C-terminal domain is important for target gene activation. Single amino acid substitutions in both the N-terminal and C-terminal domains of RhlR demonstrated that both domains possess residues involved in multimerization. RhlR with a C-terminal deletion and an RhlR site-specific mutant form that possessed multimerization but not transcriptional activation capabilities were able to inhibit the ability of wild-type RhlR to activate rhlA expression in P. aeruginosa. We conclude that C₄-HSL binding is necessary for RhlR multimerization and that RhlR functions as a multimer in P. aeruginosa.

This article has been cited by other articles:

• Castang, S., Reverchon, S., Gouet, P., Nasser, W. (2006). Direct Evidence for the Modulation of the Activity of the Erwinia chrysanthemi Quorum-sensing Regulator ExpR by Acylhomoserine Lactone Pheromone. J. Biol. Chem. 281: 29972-29987 [Abstract] [Full Text]  
• Koch, B., Liljefors, T., Persson, T., Nielsen, J., Kjelleberg, S., Givskov, M. (2005). The LuxR receptor: the sites of interaction with quorum-sensing signals and inhibitors. Microbiology 151: 3589-3602 [Abstract] [Full Text]