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Transcript of Quorum Sensing
November 24, 2009 Communication As the population of bacteria increase, the signal concentration also increases... Optimal concentrations = altered gene expression Quorum Quenching Discovered Vibrio fischeri a symbiotic species that provides its marine eukaryotic hosts with light Corn Plants Pantoea stewartii subsp. stewartii Two serious crop diseases leaf blight on maize Stewart's wilt on sweet corn bacteria is able to cause disease because of EPS capsule Bacteria release signalling molecules that are detected by surrounding bacteria Tobacco Plants Fuchs, Leonhart. Tobacco Plant. 1542. Web. Web. 11 Nov. 2009. <http://www.spamula.net/blog/i41/non3.jpg>. Corn Plant. Web. 11 Nov. 2009. <www.orientnew.us/wp/lw/photo/Corn-plant.jpg> QS Genes LuxI LuxR LuxS Autoinducers N-acyl homoserine lactones References References The Cephalopod Page. www.thecephalopodpage.org/Escolopes.php.
Dong, Y. and L. Zhang. 2005. Quorum sensing and quorum-quenching enzymes. J. Microbiol. 43(S): 101-109.
Gray, K. M., and J. R. Garey. 2001. The evolution of bacterial LuxI and LuxR quorum sensing regulators. Microbiol. 147: 2379-2387.
Lerat, E., and N. A. Moran. 2004. The evolutionary history of quorum-sensing systems in bacteria. Mol. Biol. Evol. 21(5): 903-913.
Nadell. C. D., et al. 2008. The evolution of quorum sensing in bacterial biofilms. PLoS Biol. 6(1): 0171-0179.
Waters, C. M., and B. L. Bassler. 2005. Quorum sensing: cell-to-cell communication in bacteria. Annu. Rev. Cell Dev. Biol. 21: 319-346. Current Research Cystic Fibrosis www.apsnet.org/education/advancedplantpath/LabExercises/BacteriaSignaling/Images/fig1.gif QS is not just seen in prokaryotic organisms luminescence, antibotic production, plasmid transfer, motility, virulence and biofilm formation Quenching enzyme activity has been documented in at least 10 bacterial species these organisms belong to three phyla in bacterial kingdom: Actinobacteria, Firmicutes, and Proteobacteria AHL-acylases degradation activity is most likely due to the paraoxonases encoded by the PON genes Downregulation of suspected QS quenching enzyme Most patients die of bacterial infections in lungs Biofilm present in infections indicating QS bacteria are responsible control biosynthesis of AHLs controls synthesis of proteins that act as specific response elements autoinducer is not AHL but a furanosyl borate diester Agrobacterium tumefaciens Kin-selection Cases of sacrifice Myxococcus xanthus Bacteria benefit from group activites that may be unattainable to bacterium acting alone Selection for maintenance of QS mutants are outcompeted by wild-type Quorum quenching:
an antibiotic alternative Evolutionary Implications of QS