Team:StanfordBrownSpelman/Cellulose Cross Linker

From 2014.igem.org

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<h6><b></b>Our initial approach was to use the cellulose binding domains from <i>C. cellulovorans </i>  <a href="http://parts.igem.org/Part:BBa_K863111">(part BBa_K863111)</a></a> on either side of the streptavidin domain <a href="http://parts.igem.org/Part:BBa_K283010">(part BBa_K283010) under a T7 promoter in the PSB1A3 backbone.</a></a>We then express  the cross-linker protein in <i> E. coli </i>. We included a His-Tag to purify the protein. Once purified, the cross-linking protein is tested on bacterial cellulose we grew in our lab from the organism <i>G. hansenii</i>. By dotting the protein on the cellulose, the cellulose binding domains will bind to the cellulose fibers and leave the streptavidin domain unbound, but ready to bind biotin.</center></h6>
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<div class="sub4"><a href="http://docs.google.com/document/d/1-BS2AXdxk_gbYPC2qc5T6e1L7qtnXg4DxsOF-aoxIQg/edit?usp=sharing" target="_blank"><img src="https://static.igem.org/mediawiki/2014/2/25/SBS_iGEM_2014_download.png"></a><a href="http://docs.google.com/document/d/1-BS2AXdxk_gbYPC2qc5T6e1L7qtnXg4DxsOF-aoxIQg/edit?usp=sharing">Click here to go to our project journal, which details our design and engineering process and included descriptions of the protocols we developed and used.</a></div>
<div class="sub4"><a href="http://docs.google.com/document/d/1-BS2AXdxk_gbYPC2qc5T6e1L7qtnXg4DxsOF-aoxIQg/edit?usp=sharing" target="_blank"><img src="https://static.igem.org/mediawiki/2014/2/25/SBS_iGEM_2014_download.png"></a><a href="http://docs.google.com/document/d/1-BS2AXdxk_gbYPC2qc5T6e1L7qtnXg4DxsOF-aoxIQg/edit?usp=sharing">Click here to go to our project journal, which details our design and engineering process and included descriptions of the protocols we developed and used.</a></div>
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Revision as of 16:08, 17 October 2014

Stanford–Brown–Spelman iGEM 2014 — Cellulose Acetate

Approach & Methods


Figure 1. An illustration of cellulose binding domains cross-linking cellulose fibers with a streptavidin domain in the middle. The biosensing cell is expressing a biotinylated AviTag which will bind to the streptavidin .


Our initial approach was to use the cellulose binding domains from C. cellulovorans (part BBa_K863111) on either side of the streptavidin domain (part BBa_K283010) under a T7 promoter in the PSB1A3 backbone.We then express the cross-linker protein in E. coli . We included a His-Tag to purify the protein. Once purified, the cross-linking protein is tested on bacterial cellulose we grew in our lab from the organism G. hansenii. By dotting the protein on the cellulose, the cellulose binding domains will bind to the cellulose fibers and leave the streptavidin domain unbound, but ready to bind biotin.
Results
Our initial approach was to include two identical cellulose-binding domains on either side of the streptavidin domain. Due to the repetitive nature of the sequence and potential homologous recombination, we had many issues with molecular cloning. We changed our approach to using two different cellulose-binding domains with different sequences. This allowed us to successfully conduct the molecular cloning.


Figure 2. Sequencing data for the cross-linking protein. The solid green bar indicates a perfect match between our sequence and the expected sequence.The first 1000 base pairs are sequenced in this forward sequence.


Figure 3. Sequencing data for the cross-linking protein. The solid green bar indicates a perfect match between our sequence and the expected sequence.The last 1000 base pairs are sequenced in this reverse sequence. This in combination with the perfect sequencing of the first 1000 base pairs shows our construct matches the CBD-Streptavidin-CBD protein exactly.
References
1. M Linder and T T Teeri (1996) The cellulose-binding domain of the major cellobiohydrolase of Trichoderma reesei exhibits true reversibility and a high exchange rate on crystalline cellulose. PNAS 122251 PMID: 24136966.

2. Claire E. CHIVERS, Apurba L. KONER, Edward D. LOWE and Mark HOWARTH (2011) How the biotin–streptavidin interaction was made even stronger: investigation via crystallography and a chimaeric tetramerBiochem.J. 55 PMID: 2981802.
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