Thu, 21 Aug 2008 15:32:12 BST CiteULike: bakakaj's Wagner http://www.citeulike.org/user/bakakaj/author/Wagner CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/bakakaj/article/2905219 <i>J. Bacteriol., Vol. 189, No. 21. (1 November 2007), pp. 7752-7764.</i><br /><br />AlgR controls numerous virulence factors in Pseudomonas aeruginosa, including alginate, hydrogen cyanide production, and type IV pilus-mediated twitching motility. In this study, the role of AlgR in biofilms was examined in continuous-flow and static biofilm assays. Strain PSL317 (DeltaalgR) produced one-third the biofilm biomass of wild-type strain PAO1. Complementation with algR, but not fimTU-pilVWXY1Y2E, restored PSL317 to the wild-type biofilm phenotype. Comparisons of the transcriptional profiles of biofilm-grown PAO1 and PSL317 revealed that a number of quorum-sensing genes were upregulated in the algR deletion strain. Measurement of rhlA::lacZ and rhlI::lacZ promoter fusions confirmed the transcriptional profiling data when PSL317 was grown as a biofilm, but not planktonically. Increased amounts of rhamnolipids and N-butyryl homoserine lactone were detected in the biofilm effluent but not the planktonic supernatants of the algR mutant. Additionally, AlgR specifically bound to the rhlA and rhlI promoters in mobility shift assays. Moreover, PAO1 containing a chromosomal mutated AlgR binding site in its rhlI promoter formed biofilms and produced increased amounts of rhamnolipids similarly to the algR deletion strain. These observations indicate that AlgR specifically represses the Rhl quorum-sensing system during biofilm growth and that such repression is necessary for normal biofilm development. These data also suggest that AlgR may control transcription in a contact-dependent or biofilm-specific manner. 10.1128/JB.01797-06 Pseudomonas aeruginosa AlgR Represses the Rhl Quorum-Sensing System in a Biofilm-Specific Manner Lisa Morici Alexander Carterson Victoria Wagner Anders Frisk Jill Schurr Zu Daniel Hassett Barbara Iglewski Karin Sauer Michael Schurr doi:10.1128/JB.01797-06 J. Bacteriol., Vol. 189, No. 21. (1 November 2007), pp. 7752-7764. 2008-06-18T11:51:51-00:00 2007 J. Bacteriol. 189 21 7752 7764 aeruginosa alginate algr qs http://www.citeulike.org/user/bakakaj/article/1069701 <i>Analytical and Bioanalytical Chemistry, Vol. 387, No. 2. (January 2007), pp. 469-479.</i> Analysis of the hierarchy of quorum-sensing regulation in Pseudomonas aeruginosa Wagner Victoria Li Luen-Luen Isabella Vincent Iglewski Barbara doi:10.1007/s00216-006-0964-6 Analytical and Bioanalytical Chemistry, Vol. 387, No. 2. (January 2007), pp. 469-479. 2007-01-26T19:11:17-00:00 2007 Analytical and Bioanalytical Chemistry 1618-2642 387 2 469 479 Springer aeruginosa lettuce qs http://www.citeulike.org/user/bakakaj/article/952427 <i>J Bacteriol, Vol. 185, No. 7. (April 2003), pp. 2080-2095.</i><br /><br />Bacterial communication via quorum sensing (QS) has been reported to be important in the production of virulence factors, antibiotic sensitivity, and biofilm development. Two QS systems, known as the las and rhl systems, have been identified previously in the opportunistic pathogen Pseudomonas aeruginosa. High-density oligonucleotide microarrays for the P. aeruginosa PAO1 genome were used to investigate global gene expression patterns modulated by QS regulons. In the initial experiments we focused on identifying las and/or rhl QS-regulated genes using a QS signal generation-deficient mutant (PAO-JP2) that was cultured with and without added exogenous autoinducers [N-(3-oxododecanoyl) homoserine lactone and N-butyryl homoserine lactone]. Conservatively, 616 genes showed statistically significant differential expression (P </= 0.05) in response to the exogenous autoinducers and were classified as QS regulated. A total of 244 genes were identified as being QS regulated at the mid-logarithmic phase, and 450 genes were identified as being QS regulated at the early stationary phase. Most of the previously reported QS-promoted genes were confirmed, and a large number of additional QS-promoted genes were identified. Importantly, 222 genes were identified as being QS repressed. Environmental factors, such as medium composition and oxygen availability, eliminated detection of transcripts of many genes that were identified as being QS regulated. Microarray analysis of Pseudomonas aeruginosa quorum-sensing regulons: effects of growth phase and environment. VE Wagner D Bushnell L Passador AI Brooks BH Iglewski J Bacteriol, Vol. 185, No. 7. (April 2003), pp. 2080-2095. 2006-11-20T01:20:29-00:00 2003 J Bacteriol 0021-9193 185 7 2080 2095 aeruginosa qs transcriptomics http://www.citeulike.org/user/bakakaj/article/2394697 <i>Trends in Microbiology, Vol. 14, No. 2. (February 2006), pp. 55-58.</i><br /><br />A recent study suggests that the opportunistic pathogen Pseudomonas aeruginosa can actively monitor the host immune system. The P. aeruginosa outer membrane protein OprF was found to bind specifically to the cytokine interferon-[gamma] (IFN-[gamma]), and this interaction upregulated production of virulence factors through a cell-cell communication system known as quorum sensing (QS). Taken together with previous findings that P. aeruginosa QS can alter the host immune response (e.g. by activation of IFN-[gamma]), these data illustrate an exciting new element of bacteria-host interactions in which the P. aeruginosa quorum-sensing system both senses and modulates the host immune state. Quorum sensing: dynamic response of Pseudomonas aeruginosa to external signals Victoria Wagner John Frelinger Richard Barth Barbara Iglewski doi:10.1016/j.tim.2005.12.002 Trends in Microbiology, Vol. 14, No. 2. (February 2006), pp. 55-58. 2008-02-18T15:12:40-00:00 2006 Trends in Microbiology 14 2 55 58 aeruginosa qs review http://www.citeulike.org/user/bakakaj/article/1362277 <i>Proc Natl Acad Sci U S A, Vol. 104, No. 19. (8 May 2007), pp. 8101-8106.</i><br /><br />The metabolically versatile Gram-negative bacterium Pseudomonas aeruginosa inhabits terrestrial, aquatic, animal-, human-, and plant-host-associated environments and is an important causative agent of nosocomial infections, particularly in intensive-care units. The population genetics of P. aeruginosa was investigated by an approach that is generally applicable to the rapid, robust, and informative genotyping of bacteria. DNA, amplified from the bacterial colony by circles of multiplex primer extension, is hybridized onto a microarray to yield an electronically portable binary multimarker genotype that represents the core genome by single nucleotide polymorphisms and the accessory genome by markers of genomic islets and islands. The 240 typed P. aeruginosa strains of diverse habitats and geographic origin segregated into two large nonoverlapping clusters and 45 isolated clonal complexes with few or no partners. The majority of strains belonged to few dominant clones widespread in disease and environmental habitats. The most frequent genotype was represented by the sequenced strain PA14. Core and accessory genome were found to be nonrandomly assembled in P. aeruginosa. Individual clones preferred a specific repertoire of accessory segments. Even the most promiscuous genomic island, pKLC102, had integrated preferentially into a subset of clones. Moreover, some physically distant loci of the core genome, including oriC, showed nonrandom associations of genotypes, whereas other segments in between were freely recombining. Thus, the P. aeruginosa genome is made up of clone-typical segments in core and accessory genome and of blocks in the core with unrestricted gene flow in the population. Population structure of Pseudomonas aeruginosa. L Wiehlmann G Wagner N Cramer B Siebert P Gudowius G Morales T Köhler C van Delden C Weinel P Slickers B Tümmler doi:10.1073/pnas.0609213104 Proc Natl Acad Sci U S A, Vol. 104, No. 19. (8 May 2007), pp. 8101-8106. 2007-06-04T10:34:37-00:00 2007 Proc Natl Acad Sci U S A 0027-8424 104 19 8101 8106 genotyping pseudomonas