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Team:Grenoble/Projet/Design/quorum
From 2011.igem.org
The Quorum Sensing
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The Toggle Switch allows our bacterial strain to switch between one of the two different behaviors (Receiver or Secretor) depending on the predominant concentration in the external medium: IPTG or Hg. We take into account two proteins repressing (CinI/CinR) each other's expression (pLac/pMerT). We create the fundaments of a toggle system that can switch when using two inducers in the medium: IPTG and Hg. |
Initially, both genes, MerR and LacI, are expressed repressing each other promoters: pLac and pMerT.
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On the plate where Hg concentration is the uppermost, this inducer will remove the repression exerted on pMerT promoter. So, the LacI proteins will be expressed and by repressing the promoter pLac, LacI proteins are shutting down the other way of the toggle. |
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Inversely, where IPTG concentration is the uppermost, the other way will be activated. |
Coloration
The two populations encounter each other at the “interface”. At this location cells emit AHL closely to receivers.
The AHL molecules enter into the receiving cells and bind receptor protein to form a complex to up-regulate the promoter pCin. Allowing the expression of the three Lycopene synthesise enzymes coding crtB, crtE, crtI. These three enzymes produce the lycopene so we can observe a red stripe at the interface between receiving and senders.
