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Team:Chiba/Project
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Project overview
E.coli time manager
We control the timing of gene expression by using multiple signaling devices.To this end,we utilize molecules associated with Quorum sensing, a phenomenon that allows bacteria to communicate with each other.Our project uses two classes of bacteria: senders and receivers. Senders produce signaling molecules, and Receivers are activated only after a particular concentration of this molecule is reached.Although different quorum sensing species have slightly different signaling molecules, these molecules are not completely specific to their hosts and cross-species reactivity is observed (M.K Winson et al.FEMS Microbiology Letters 1998).Communication using non-endogenous molecules is less sensitive, andrequires a higher signal concentration to take effect.This results in slower activation of receivers.
Project Design
About Quorum Sensing
Quorum sensing is a cell-to-cell signaling action of bacteria. They detect the cell density of the same species and coordinate the expression behavior of their cells. Species of Gram-Negative signaling transfer molecules (so-called autoinducer) is a series of acyl homoserine lactone (AHL). The signals are synthesized from precursors by a synthase protein, “I,” and once they have reached a certain threshold concentration, they bound to a transcriptional activating “R” protein to induce expression of target genes.
Controlling the time of a cell-to-cell signaling action
Our project uses two classes of bacteria: senders and receivers. Senders produce signaling molecules, and Receivers are activated only after a particular concentration of this molecule is reached.When signal concentration is increasing
- Quorum-Sensing Cross-talk
Species-specific quorum sensing in Gram-negative bacteria is mediated by acylhomoserine lactones (AHLs) with various moieties distinguishing signals among species.AHLs produced by different bacteria differ only in the length of the acyl-chain moiety and substitution at position C3.(BBa_F2620:Specificity)
- LuxR/Plux mutants show
- a greater response to 3OC6HSL (C. H. Collins.et al.Mol.Microbiol.2005.)
- a increase in sensitivity to 3OC12HSL (B. Koch.et al.Microbiology (2005)).
Experiments
AHL signaling test
- Senders
Method
- Transform Senders into E.coli strains(JW1908/XL10GOLD) and Receiver into Ecoli strain(JW1908).
- Inoculated them independently in liquid media. Incubated at 37℃ 12h.
- Washed Senders and receiver.
- Mix them.
- Incubated at 37℃ or 30℃.
- Measured intensity of green fluorescence at regular time intervals.
Results
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