Winzer, Klaus and Falconer, Colin and Garber, Nachman C. and Diggle,, Stephen P. and Camara, Miguel and Williams, Paul (2000) The Pseudomonas aeruginosa Lectins PA-IL and PA-IIL Are Controlled by Quorum Sensing and by RpoS. Journal of Bacteriology, 182 (22). pp. 6401-6411. ISSN 0021-9193
Full text not available from this repository.Abstract
In Pseudomonas aeruginosa, many exoproduct virulence determinants are regulated via a hierarchical quorum-sensing cascade involving the transcriptional regulators LasR and RhlR and their cognate activators, N-(3-oxododecanoyl)-L-homoserine lactone (3O-C12-HSL) and N-butanoyl-L-homoserine lactone (C4-HSL). In this paper, we demonstrate that the cytotoxic lectins PA-IL and PA-IIL are regulated via quorum sensing. Using immunoblot analysis, the production of both lectins was found to be directly dependent on the rhl locus while, in a lasR mutant, the onset of lectin synthesis was delayed but not abolished. The PA-IL structural gene, lecA, was cloned and sequenced. Transcript analysis indicated a monocistronic organization with a transcriptional start site 70 bp upstream of the lecA translational start codon. A lux box-type element together with RpoS (S) consensus sequences was identified upstream of the putative promoter region. In Escherichia coli, expression of a lecA::lux reporter fusion was activated by RhlR/C4-HSL, but not by LasR/3O-C12-HSL, confirming direct regulation by RhlR/C4-HSL. Similarly, in P. aeruginosa PAO1, the expression of a chromosomal lecA::lux fusion was enhanced but not advanced by the addition of exogenous C4-HSL but not 3O-C12-HSL. Furthermore, mutation of rpoS abolished lectin synthesis in P. aeruginosa, demonstrating that both RpoS and RhlR/C4-HSL are required. Although the C4-HSL-dependent expression of the lecA::lux reporter in E. coli could be inhibited by the presence of 3O-C12-HSL, this did not occur in P. aeruginosa. This suggests that, in the homologous genetic background, 3O-C12-HSL does not function as a posttranslational regulator of the RhlR/C4-HSL-dependent activation of lecA expression.
| Item Type: | Article |
|---|---|
| Journal or Publication Title: | Journal of Bacteriology |
| Subjects: | Q Science > QH Natural history > QH301 Biology |
| Departments: | Faculty of Health and Medicine > Biomedical & Life Sciences |
| ID Code: | 9563 |
| Deposited By: | Dr Klaus Winzer |
| Deposited On: | 16 Jun 2008 11:12 |
| Refereed?: | Yes |
| Published?: | Published |
| Last Modified: | 26 Jul 2012 18:38 |
| Identification Number: | |
| URI: | http://eprints.lancs.ac.uk/id/eprint/9563 |
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