Team:Calgary/Lab
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<div class="heading">General Model</div> | <div class="heading">General Model</div> | ||
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- | In Vibrio harveyi, the quorum sensing signal is induced by a molecule called AI-2. AI-2 is bound to the protein LuxP in the periplasm, and the LuxP-AI-2 complex interacts with another membrane-bound sensor histidine kinase, LuxQ. At low cell density, with low amounts of autoinducers, LuxQ sensor acts as a kinase, autophosphorylates and transfers the phosphate to the cytoplasmic protein LuxU. LuxU transfers the phosphate to the DNA binding response regulator protein LuxO. Phosphorylated LuxO with a transcription factor | + | In Vibrio harveyi, the quorum sensing signal is induced by a molecule called AI-2. AI-2 is bound to the protein LuxP in the periplasm, and the LuxP-AI-2 complex interacts with another membrane-bound sensor histidine kinase, LuxQ. At low cell density, with low amounts of autoinducers, LuxQ sensor acts as a kinase, autophosphorylates and transfers the phosphate to the cytoplasmic protein LuxU. LuxU transfers the phosphate to the DNA binding response regulator protein LuxO. Phosphorylated LuxO with a transcription factor σ54, activates the transcription of genes encoding five regulatory small RNAs (sRNAs) termed Qrr1-5. The sRNAs bind to and destabilize the mRNA encoding the transcriptional activator, LuxR4, which is needed to activate the transcription of the luciferase operon, luxCDABE. Therefore, when there is a low cell density, the Lux R mRNA is degraded, thus the bacteria do not express bioluminescence. At higher cell density, when AI-2 concentration reaches the threshold, LuxQ sensor switches from a kinase to a phosphatase and removes the phosphate from Lux O via Lux U. Unphosphorylated LuxO cannot induce the expression of the sRNA, which in turn allows translation of LuxR mRNA, the production of Lux R and the expression of bioluminescence. |
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Revision as of 22:51, 23 July 2009
UNIVERSITY OF CALGARY