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Research Article
1 May 1991

Cloning and characterization of the Pseudomonas aeruginosa lasR gene, a transcriptional activator of elastase expression


We report the discovery of the lasR gene, which positively regulates elastase expression in Pseudomonas aeruginosa PAO1. The lasR gene was cloned by its ability to restore a positive elastase phenotype in strain PA103, a strain which possesses the elastase structural gene (lasB) but fails to synthesize the enzyme. Nucleotide sequence analysis revealed an open reading frame of 716 nucleotides encoding a protein of approximately 27 kDa. A labeled LasR protein of 27 kDa was detected in Escherichia coli by using a T7 RNA polymerase expression system. A chromosomal deletion mutant of the lasR gene was constructed in PAO1 by gene replacement. This mutant (PAO-R1) is devoid of elastolytic activity and elastase antigen. The deduced amino acid sequence of LasR is 27% homologous to the positive activator LuxR of Vibrio fischeri and the suspected activator 28K-UvrC of E. coli. Northern (RNA) analysis of total cellular RNA from PAO1, PAO-R1, and PAO-R1 containing the lasR gene on a multicopy plasmid (pMG1.7) revealed that a functional lasR gene is required for transcription of the elastase structural gene (lasB).

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Published In

cover image Journal of Bacteriology
Journal of Bacteriology
Volume 173Number 9May 1991
Pages: 3000 - 3009
PubMed: 1902216


Published online: 1 May 1991


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M J Gambello
Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, New York 14642.
B H Iglewski
Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, New York 14642.

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