Team:Grenoble/Biology/AND gate


Revision as of 20:37, 26 September 2012 by Greghansen (Talk | contribs)

iGEM Grenoble 2012

In order to develop our device we needed a biological AND gate. We found a promoter which can be activated by 2 molecules : CRP-cAMP complex and the AraC protein. The paraBAD promoter has two states; in absence of L-arabinose the paraBAD promoter is repressed by AraC, whereas the the paraC promoter is activated (unless an excess of AraC is present)
In presence of L-arabinose and the CRP-cAMP complex, the promoter is activated thus enabling the transcription of the downstream elements.
This AND gate provides a filter to biological noise. Check out our main results page to for the AND gate characterization.
In order to make our AND work we need to produce cAMP. cAMP is produce by adenyl cyclase (encoded by the cyaA gene). It is an enzyme which catalyses the conversion of ATP to 3’,5’-cAMP. In Escherichia coli, cAMP is involved in carbon catabolite repression [1] and binds to the cAMP receptor protein (CRP). The corresponding complex (CRP-cAMP) is a transcriptional factor controlling the expression of more than 220 operons (Keseler et al., 2009). It has been known for a long time that E. coli actively exports cAMP into the growth medium (Goldenbaum & Hall, 1979; Makman & Sutherland, 1965).