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Journal of Bacteriology, June 2007, p. 4367-4374, Vol. 189, No. 12
0021-9193/07/$08.00+0     doi:10.1128/JB.00007-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Regulation of the Pseudomonas aeruginosa Quorum-Sensing Regulator VqsR{triangledown}

Luen-Luen Li, Jane E. Malone, and Barbara H. Iglewski*

Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642

Received 2 January 2007/ Accepted 11 April 2007

Bacteria communicate with each other to regulate cell density-dependent gene expression via a quorum-sensing (QS) cascade. In Pseudomonas aeruginosa, two known QS systems, las and rhl, control the expression of many factors that relate to virulence, pathogenicity, and biofilm development. Microarray studies of the las and rhl regulons led to our hypothesis that a complicated hierarchy in the QS regulon is composed of multiple transcriptional regulators. Here, we examined a QS-regulated gene, vqsR, which encodes a probable transcriptional regulator with a putative 20-bp operator sequence (las box) upstream. The transcriptional start site for vqsR was determined. The vqsR promoter was identified by examining a series of vqsR promoter-lacZ fusions. In addition, an Escherichia coli system where either LasR or RhlR protein was expressed from a plasmid indicated that the las system was the dominant regulator for vqsR. Electrophoretic mobility shift assays (EMSA) demonstrate that purified LasR protein binds directly to the vqsR promoter in the presence of 3O-C12-HSL. Point mutational analysis of the vqsR las box suggests that positions 3 and 18 in the las box are important for vqsR transcription, as assayed with a series of vqsRp-lacZ fusions. EMSA also shows that positions 3 and 18 are important for binding between the vqsR promoter and LasR. Our results demonstrate that the las system directly regulates vqsR, and certain nucleotides in the las box are crucial for LasR binding and activation of the vqsR promoter.

* Corresponding author. Mailing address: Department of Microbiology and Immunology, Box 672, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642. Phone: (585) 275-3402. Fax: (585) 473-9573. E-mail: bigl{at}mail.rochester.edu

{triangledown} Published ahead of print on 20 April 2007.

Journal of Bacteriology, June 2007, p. 4367-4374, Vol. 189, No. 12
0021-9193/07/$08.00+0     doi:10.1128/JB.00007-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Huang, J., Xu, Y., Zhang, H., Li, Y., Huang, X., Ren, B., Zhang, X. (2009). Temperature-Dependent Expression of phzM and Its Regulatory Genes lasI and ptsP in Rhizosphere Isolate Pseudomonas sp. Strain M18. Appl. Environ. Microbiol. 75: 6568-6580 [Abstract] [Full Text]  


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