Team:Grenoble/Project/Main Results


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iGEM Grenoble 2012


Main results

This part will present the pre-regional Jamboree main results.

Simple amplification loop

In a first place, biologists and modellers worked on a simple amplification loop.

The modellers proved that a simple amplification loop could not work. There is no state where GFP is not expressed.

Why an AND gate ?

The team thought that an AND gate could be our solution. It could add a biological noise filter and resolve the problem of the continuous expression of GFP.

Modelling results confirmed that built system will work.

Biological results

Biological AND gate test.

As you can see the paraBAD works as expected. We began the construction of the amplification loop (paraBAD_gfp_cyaA).

Issues encountered

We have not yet constructed that part. We had some problem with the ligation procedure. Another explanation could be that our bacteria are transformed with the right construction leading to an over-expression of Adenylate cyclase which is lethal: this can be attributed to the fact that overproduction of cAMP is lethal to Escherichia coli possibly due to an accumulation of methylglyoxal[1][2].

And after?

In the future weeks (according to ours results) we will try to make the culture of our transformed bacteria in a medium complement with glucose and acetate.
A possible track would be to add another regulation system on the adenylate cyclase production with the riboswitch RsmA/rsmY.


[1] Accumulation of Toxic Concentrations of Methylglyoxal by Wild-Type Escherichia coli K-12, Rollie S. Ackerman, Nicholas R. Cozzarelli and Wolfgang Epstein
[2] Metabolic flux analysis of Escherichia coli in glucose-limited continuous culture. II. Dynamic response to famine and feast, activation of the methylglyoxal pathway and oscillatory behaviour Jan Weber†, Anke Kayser‡ and Ursula Rinas