Team:Amsterdam/project/molecular design

From 2012.igem.org

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function writerText(){
function writerText(){
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     $('#moldesign-content').append("<h1>What does a sensor mean to the Cellular Logbook?</h1> <br\>A logbook aims to store the occurrence, encounter or presence of a external signal. Whether this signal comes from a metabolite, a chemical or a toxin, compound or substrate, doesn’t matter! What’s matter is if the signal can be taken up by the cell and activates a promoter that will induce the transcription of our “writer” protein. Therefore any well-characterized promoter in the parts registry can be used… <br\> For our proof-of-concept we chose as sensors to implement two different promoters:
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Lac-hybrid promoter:
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The lac promoter and its different protein components have been studied for decades and it is widely used as one of the common systems for recombinant protein production in Escherichia coli.
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On its repressive state, the LacI repressor, an allosteric protein constitutively expressed by E. Coli, binds the promoter with a high affinity, preventing transcription to occur. One bound by an inducer, either lactose or IPTG, the repressor is release from the promoter and the RNA polymerase complex could be formed.
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Our first sensor uses the lac-hybrid promoter (R0011) together with a medium/weak ribosomal binding site (R0032). Derived from the original Lac Operon (BBa_R0010) this adaptation does not rely on the presence of glucose, but only on lactose.
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Arabinose promoter:
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This promoter derived from the wild-type version present in E. coli and has a modified AraI1 site, which cause this promoter to be less responsive to low concentrations of induction and exhibit a lower maximum response.
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The pBAD is very specifically activated by L-Arabinose. In the absence of arabinose the repressor protein AraC binds to AraI1 AraO2, blocking transcription. In the presence of arabinose, AraC binds to it and changes its conformation such that it interacts with the AraI1 and AraI2 operator sites, allowing transcription.
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For the characterization of our system, we choose the a weak version of the promoter, the pBAD-weak, taken from the parts registry (BBa_K206001).")
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Revision as of 19:01, 26 September 2012