Project.html

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<img src="https://static.igem.org/mediawiki/2013/0/0a/U42_normal.png" class="raw_image">
 
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<b>Abstract</b>
 
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<p>The human peptide LL-37 is a cationic antimicrobial peptide with activity against Gram-negative and Gram-positive bacteria. It has been shown to protect against <i>Helicobacter pylori</i> infection and its related gastritis, besides of inhibiting the growth of other pathogenic bacteria in the gastrointestinal tract such as <i>Salmonella typhimurium</i> and <i>Escherichia coli.</i> Most of the current synthetic expression systems for LL-37 depend on the construction of soluble fusion partners to avoid cytotoxic effects of the antimicrobial peptide in the <i>E. coli</i> host strain. However, these fusion systems require additional cleavage steps using enzymatic or chemical methods, which makes them impossible to express an active LL-37 peptide in vivo. In order to create a resistant host that can export LL-37 to the media, we intend to overexpress the <i>E. coli</i> acrAB and tolC operons, which activate the AcrAB-TolC efflux pump, a mechanism that has been related with resistance to this and similar antimicrobial peptides by expulsion. Our aim is to create a system in which <i>E. coli</i> expels LL-37 only when H. pylori or other pathogenic bacteria, such as <i>S. typhimurium, E. coli</i> or <i>V. cholerae</i>, are present. In order to do this we are using the LsrA promoter, which allows transcription in the presence of AI-2, a molecule produced by bacteria to communicate via quorum-sensing. <i>E. coli</i> also produces AI-2, so we designed an antisense RNA with specific secondary structure to inhibit the translation of LuxS, the enzyme responsible of the production of AI-2 in <i>E. coli</i>. </p>
 
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Latest revision as of 18:41, 25 August 2013