Team:SMTexas/Design

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<h3> aldB Gene (Detects Ethanol) </h3>
<h3> aldB Gene (Detects Ethanol) </h3>
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The aldB gene, which codes for a functional aldehyde dehydrogenase is induced by ethanol, a VOC that exists in higher concentrations in the  breath of lung cancer patients. In E. Coli, the metabolism of ethanol consists of its transformation into an aldehyde and then into a carboxylic acid. The latter product then reacts with the g protein receptor, thus triggering a series of reactions that eventually effects the Crp-cAMP complex, a dual regulator complex that regulates the expression of the DNA sequence. cAMP binds to Crp, thus changing the form of Crp, and this newly conformed Crp attaches to the promoter, increasing the affinity of the DNA sequence to RNA Polymerase. Crp is also known as CAP, which stands for catabolite activator protein and is present in E. Coli under normal conditions. After RNA Polymerase binds to the promoter and then initiates transcription. By placing GFP after the aldB coding sequence, we will ensure that GFP is also expressed and thus, in the presence of ethanol, the bacteria will glow.<br>
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The aldB gene codes for a functional aldehyde dehydrogenase, which is directly induced by ethanol. Metabolism of the alcohol consists of its transformation into an aldehyde and then into a carboxylic acid in activating several related pathways. The acid reacts with the BarA histidine sensory kinase, a signalling enzyme involved in a two component signal transduction system present in E. coli, to catalyze the breakdown of various carboxylic acids. The kinase is additionally responsible for the induction of RpoS, a regulatory gene of aldB that directly opposes fis during the activation of the aldB operon. Eventually, BarA triggers a series of vital reactions that affect the Crp-cAMP regulatory mechanism, a dual complex that controls the expression of the aldB coding sequence. In the complex, cAMP conforms the shape of Crp, also known as CAP (catabolite activator protein). This newly conformed Crp then attaches to the promoter and contributes to the initiation of transcription of the aldB operon. Downstream of aldB, CFP (cyan fluorescent protein) is expressed and the bacteria exhibits cyan fluorescence.<br>
<table><tr><td width="1200" align="center"><img src="https://static.igem.org/mediawiki/2014hs/7/74/AldB_Map.png"></td></tr></table>  
<table><tr><td width="1200" align="center"><img src="https://static.igem.org/mediawiki/2014hs/7/74/AldB_Map.png"></td></tr></table>  

Revision as of 16:58, 19 June 2014