Template:Nevada/TheCoronatineSystem

From 2014.igem.org

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                                         <p>TIR1 is the E3 ubiquitin ligase associated with the Auxin pathway. It is currently the best known F-box protein for integration into yeast, as other F-box proteins from Arabidopsis have acclimated to less thermally variable environments and have low efficiency and expression in yeast cells. TIR1, when loaded with auxin, will bind more efficiently to its substrate, our protein of interest, and will attract ubiquitin to this complex as a signal for degradation. Once ubiquitinated, this whole complex is sent to the 26s proteasome for digestion. We modified TIR1 with a Myc tag for verification once integrated into yeast cells. </p>
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                                         <p>COI1 is the E3 ubiquitin ligase for the JAZ degron pathway. This is analogous to the TIR1 enzyme in the auxin pathway, but instead it binds coronatine. Normally, COI1 binds JA-Ile (jasmonic acid-isoleucine) but this compound is difficult and expensive to synthesize and cannot be purchased. Coronatine is structurally similar and is manufactured, which is why we used it instead. COI1 was amplified and verified through gel electrophoresis. </p>
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                                         <p>Amplified and tagged TIR1 was then engineered to join a promoter, pTEF, and a reporter, GFP. This whole insert was attached to a bacterial vector and transformed with NEB 10 beta competent cells onto LB-ampicillin agar plates in the preliminary stages. After successful colony growth, we extracted this DNA, purified it, and transformed into yeast cells. Initially we had used an ADH1 promoter but kept producing errors. We switched to a promoter known to work not only with GFP but also with yeast, since that was our final destination. </p>
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                                         <p>Just like we tagged TIR1 with Myc, here we tagged COI1 with an HA tag for screening. Amplified and tagged COI1 was then joined to pTEF-GFP, inserted into a bacterial vector and transformed with NEB 10 beta competent cells with LB-ampicillin selection. You may have noticed that we use GFP in both of our systems, though we said our goal was a bioorthogonal system to degrade two proteins simultaneously. At the beginning, our use of RFP was not very successful, so for the interest of making sure we can build a construct that works, we used what we had which was GFP and will later swap it out for mCherry when we juxtapose the systems into yeast. </p>
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                                         <p>After miniprep of DNA, the newly engineered vector was linearized and transformed into W303 yeast cells. It was screened via yeast colony PCR.</p>
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                                         <p>After the above construct grew successful colonies, we isolated and purified the newly engineered vector and transformed into W303 yeast cells. It was screened via yeast colony PCR.</p>
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                                             <a  title="Confirmation of TIR1 expression in yeast">
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                                                 <b>Confirmation of TIR1 expression in yeast</b>
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                                                 <b>Confirmation of COI1 expression in yeast</b>
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                                         <p>Green fluorescent protein was extracted from yeast via alkali treatment and analyzed on a Western blot and Coomassie blue assay. Our positive control included GFP from bacteria. We wanted to know that GFP was indeed successfully integrated into W303 yeast cells before our next step, adding auxin. After confirmation of GFP, and after the addition of auxin, we would expect to not see GFP on a Western blot since our whole project is based on its degradation.  </p>
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                                         <p>Protein was extracted from yeast via alkali treatment and analyzed on a Western blot and Coomassie blue assay.  </p>
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Revision as of 21:19, 17 October 2014

APP ON Blog

Team Nevada

The BAITswitch

The Bioorthoginal Auxin Induceable Trigger Switch
Post Image

Amplification of E3 ubiquitin ligase

COI1 is the E3 ubiquitin ligase for the JAZ degron pathway. This is analogous to the TIR1 enzyme in the auxin pathway, but instead it binds coronatine. Normally, COI1 binds JA-Ile (jasmonic acid-isoleucine) but this compound is difficult and expensive to synthesize and cannot be purchased. Coronatine is structurally similar and is manufactured, which is why we used it instead. COI1 was amplified and verified through gel electrophoresis.

Post Image

Gibson Assembly and E. coli transformation

Just like we tagged TIR1 with Myc, here we tagged COI1 with an HA tag for screening. Amplified and tagged COI1 was then joined to pTEF-GFP, inserted into a bacterial vector and transformed with NEB 10 beta competent cells with LB-ampicillin selection. You may have noticed that we use GFP in both of our systems, though we said our goal was a bioorthogonal system to degrade two proteins simultaneously. At the beginning, our use of RFP was not very successful, so for the interest of making sure we can build a construct that works, we used what we had which was GFP and will later swap it out for mCherry when we juxtapose the systems into yeast.

Post Image

Integration of Engineered Vectors into Yeast Cells

After the above construct grew successful colonies, we isolated and purified the newly engineered vector and transformed into W303 yeast cells. It was screened via yeast colony PCR.

Post Image

Confirmation of COI1 expression in yeast

Protein was extracted from yeast via alkali treatment and analyzed on a Western blot and Coomassie blue assay.