Skip to main content
PMC home page
Journal of Bacteriology logoLink to Journal of Bacteriology
. 1995 Feb;177(3):654–659. doi: 10.1128/jb.177.3.654-659.1995

Activation of the Pseudomonas aeruginosa lasI gene by LasR and the Pseudomonas autoinducer PAI: an autoinduction regulatory hierarchy.

P C Seed 1, L Passador 1, B H Iglewski 1
PMCID: PMC176640  PMID: 7836299

Abstract

In Pseudomonas aeruginosa, the transcriptional activator LasR and the Pseudomonas autoinducer PAI, are necessary for efficient transcriptional activation of the lasB gene, encoding elastase (L. Passador, J. M. Cook, M.J. Gambello, L. Rust, and B. H. Iglewski, Science 260:1127-1130, 1993). The transcriptional start points of lasI in Escherichia coli and P. aeruginosa were determined by S1 nuclease mapping. In the presence of both LasR and PAI, the start site, T1, is located at position -25 relative to the ATG translational start codon. A minor transcriptional start, T2, is found at position -13 when lasI is transcribed in the absence of either LasR or PAI in P. aeruginosa and E. coli, respectively. To begin to closely examine the regulation of lasI, whose product is involved in the synthesis of PAI, a lasI-lacZ fusion on a lambda phage was constructed to form monolysogens of E. coli MG4. Lysogens supplied only with either lasI or lasR via multicopy plasmids demonstrated no significant increase in beta-galactosidase expression compared with control levels. Lysogens in which both lasR and lasI were supplied in multicopy exhibited a 62-fold increase in expression, and a lysogen in which lasR was supplied in trans and which was grown in the presence of exogenous PAI exhibited a 60-fold increase. Thus, LasR and PAI are necessary for the full expression of lasI in E. coli. The interchangeability of the P. aeruginosa and Vibrio fischeri homologs LasR and LuxR and their respective autoinducers, PAI and VAI, as activators of lasI-lacZ was examined. Only the combination of LasR and PAI significantly increased the expression of lasI. The comparison of lasI-lacZ and lasB-lacZ expression lysogens grown in the presence of lasR and PAI revealed that half-maximal expression of lasI required 0.1 nM PAI, in contrast to the 1.0 nM PAI necessary for lasB half-maximal expression. These results suggest an autoinduction regulatory hierarchy in which LasR and low PAI concentrations primarily activate lasI expression in a regulatory loop. With the accumulation of PAI, secondary activation of virulence product genes such as lasB occurs.

Full Text

The Full Text of this article is available as a PDF (322.3 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Appleyard R K. Segregation of New Lysogenic Types during Growth of a Doubly Lysogenic Strain Derived from Escherichia Coli K12. Genetics. 1954 Jul;39(4):440–452. doi: 10.1093/genetics/39.4.440. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bainton N. J., Bycroft B. W., Chhabra S. R., Stead P., Gledhill L., Hill P. J., Rees C. E., Winson M. K., Salmond G. P., Stewart G. S. A general role for the lux autoinducer in bacterial cell signalling: control of antibiotic biosynthesis in Erwinia. Gene. 1992 Jul 1;116(1):87–91. doi: 10.1016/0378-1119(92)90633-z. [DOI] [PubMed] [Google Scholar]
  3. Baker T. A., Grossman A. D., Gross C. A. A gene regulating the heat shock response in Escherichia coli also affects proteolysis. Proc Natl Acad Sci U S A. 1984 Nov;81(21):6779–6783. doi: 10.1073/pnas.81.21.6779. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Deretic V., Gill J. F., Chakrabarty A. M. Gene algD coding for GDPmannose dehydrogenase is transcriptionally activated in mucoid Pseudomonas aeruginosa. J Bacteriol. 1987 Jan;169(1):351–358. doi: 10.1128/jb.169.1.351-358.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Eberhard A., Burlingame A. L., Eberhard C., Kenyon G. L., Nealson K. H., Oppenheimer N. J. Structural identification of autoinducer of Photobacterium fischeri luciferase. Biochemistry. 1981 Apr 28;20(9):2444–2449. doi: 10.1021/bi00512a013. [DOI] [PubMed] [Google Scholar]
  6. Engebrecht J., Nealson K., Silverman M. Bacterial bioluminescence: isolation and genetic analysis of functions from Vibrio fischeri. Cell. 1983 Mar;32(3):773–781. doi: 10.1016/0092-8674(83)90063-6. [DOI] [PubMed] [Google Scholar]
  7. Engebrecht J., Silverman M. Identification of genes and gene products necessary for bacterial bioluminescence. Proc Natl Acad Sci U S A. 1984 Jul;81(13):4154–4158. doi: 10.1073/pnas.81.13.4154. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Engebrecht J., Silverman M. Nucleotide sequence of the regulatory locus controlling expression of bacterial genes for bioluminescence. Nucleic Acids Res. 1987 Dec 23;15(24):10455–10467. doi: 10.1093/nar/15.24.10455. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Fuqua W. C., Winans S. C. A LuxR-LuxI type regulatory system activates Agrobacterium Ti plasmid conjugal transfer in the presence of a plant tumor metabolite. J Bacteriol. 1994 May;176(10):2796–2806. doi: 10.1128/jb.176.10.2796-2806.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Fuqua W. C., Winans S. C., Greenberg E. P. Quorum sensing in bacteria: the LuxR-LuxI family of cell density-responsive transcriptional regulators. J Bacteriol. 1994 Jan;176(2):269–275. doi: 10.1128/jb.176.2.269-275.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Gambello M. J., Iglewski B. H. Cloning and characterization of the Pseudomonas aeruginosa lasR gene, a transcriptional activator of elastase expression. J Bacteriol. 1991 May;173(9):3000–3009. doi: 10.1128/jb.173.9.3000-3009.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Gambello M. J., Kaye S., Iglewski B. H. LasR of Pseudomonas aeruginosa is a transcriptional activator of the alkaline protease gene (apr) and an enhancer of exotoxin A expression. Infect Immun. 1993 Apr;61(4):1180–1184. doi: 10.1128/iai.61.4.1180-1184.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Gray K. M., Passador L., Iglewski B. H., Greenberg E. P. Interchangeability and specificity of components from the quorum-sensing regulatory systems of Vibrio fischeri and Pseudomonas aeruginosa. J Bacteriol. 1994 May;176(10):3076–3080. doi: 10.1128/jb.176.10.3076-3080.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Hwang I., Li P. L., Zhang L., Piper K. R., Cook D. M., Tate M. E., Farrand S. K. TraI, a LuxI homologue, is responsible for production of conjugation factor, the Ti plasmid N-acylhomoserine lactone autoinducer. Proc Natl Acad Sci U S A. 1994 May 24;91(11):4639–4643. doi: 10.1073/pnas.91.11.4639. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Jones S., Yu B., Bainton N. J., Birdsall M., Bycroft B. W., Chhabra S. R., Cox A. J., Golby P., Reeves P. J., Stephens S. The lux autoinducer regulates the production of exoenzyme virulence determinants in Erwinia carotovora and Pseudomonas aeruginosa. EMBO J. 1993 Jun;12(6):2477–2482. doi: 10.1002/j.1460-2075.1993.tb05902.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Linn T., St Pierre R. Improved vector system for constructing transcriptional fusions that ensures independent translation of lacZ. J Bacteriol. 1990 Feb;172(2):1077–1084. doi: 10.1128/jb.172.2.1077-1084.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Meighen E. A. Molecular biology of bacterial bioluminescence. Microbiol Rev. 1991 Mar;55(1):123–142. doi: 10.1128/mr.55.1.123-142.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Passador L., Cook J. M., Gambello M. J., Rust L., Iglewski B. H. Expression of Pseudomonas aeruginosa virulence genes requires cell-to-cell communication. Science. 1993 May 21;260(5111):1127–1130. doi: 10.1126/science.8493556. [DOI] [PubMed] [Google Scholar]
  19. Pearson J. P., Gray K. M., Passador L., Tucker K. D., Eberhard A., Iglewski B. H., Greenberg E. P. Structure of the autoinducer required for expression of Pseudomonas aeruginosa virulence genes. Proc Natl Acad Sci U S A. 1994 Jan 4;91(1):197–201. doi: 10.1073/pnas.91.1.197. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Piper K. R., Beck von Bodman S., Farrand S. K. Conjugation factor of Agrobacterium tumefaciens regulates Ti plasmid transfer by autoinduction. Nature. 1993 Apr 1;362(6419):448–450. doi: 10.1038/362448a0. [DOI] [PubMed] [Google Scholar]
  21. Ralling G., Bodrug S., Linn T. Growth rate-dependent regulation of RNA polymerase synthesis in Escherichia coli. Mol Gen Genet. 1985;201(3):379–386. doi: 10.1007/BF00331327. [DOI] [PubMed] [Google Scholar]
  22. Schweizer H. P. Escherichia-Pseudomonas shuttle vectors derived from pUC18/19. Gene. 1991 Jan 2;97(1):109–121. doi: 10.1016/0378-1119(91)90016-5. [DOI] [PubMed] [Google Scholar]
  23. Shadel G. S., Baldwin T. O. The Vibrio fischeri LuxR protein is capable of bidirectional stimulation of transcription and both positive and negative regulation of the luxR gene. J Bacteriol. 1991 Jan;173(2):568–574. doi: 10.1128/jb.173.2.568-574.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Toder D. S., Gambello M. J., Iglewski B. H. Pseudomonas aeruginosa LasA: a second elastase under the transcriptional control of lasR. Mol Microbiol. 1991 Aug;5(8):2003–2010. doi: 10.1111/j.1365-2958.1991.tb00822.x. [DOI] [PubMed] [Google Scholar]
  25. Yanisch-Perron C., Vieira J., Messing J. Improved M13 phage cloning vectors and host strains: nucleotide sequences of the M13mp18 and pUC19 vectors. Gene. 1985;33(1):103–119. doi: 10.1016/0378-1119(85)90120-9. [DOI] [PubMed] [Google Scholar]
  26. Zhang L., Murphy P. J., Kerr A., Tate M. E. Agrobacterium conjugation and gene regulation by N-acyl-L-homoserine lactones. Nature. 1993 Apr 1;362(6419):446–448. doi: 10.1038/362446a0. [DOI] [PubMed] [Google Scholar]

Articles from Journal of Bacteriology are provided here courtesy of American Society for Microbiology (ASM)

RESOURCES