Team:Tsinghua-E/Part2

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<h2>Part 2: THU-E Tryptophan-sensor Part</h2> <br />
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  <p> Aplasmid  used for performance test of our novel tryptophan sensor.</a><br />
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   The sensor  was derived from one regulation sequence upstream of tryptophanase(tnaA) operon  in wild type <em>E. Coli</em><a href="#_ENREF_1" title="Gong, 2002 #484">3</a>. This sequence codesone 24-residue nascent peptide. Following  this nascent peptide sequence stands one transcription termination factor (Rho)  recognition sites. When certain amount of tryptophan exists, it is recognized  by the nascent peptide. This leads to the hindering of TnaC-peptidyl-tRNAPro  from being cleaved from ribosome. This peptide-mRNA-ribosome complex blocks Rho  factor’s access to its binding site which is just adjacent to termination codon  of nascent peptide so that initiate the transcription of downstream sequence. As  far as we know, this novel mechanism has not been utilized before as tryptophan  sensor. <br />
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==[[File:4_2s.png‎|40px|thumb|left]] '''Part 2: THU-E Tryptophan-sensor Part''' ==
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   As a proof of  principle, we cloned beta-lactamase gene <em>lacZ</em> downstream of wild type nascent peptide and Rho interaction sequence. The  assembly was cloned between the NcoI and BamHI sites of pTrc99A vector with  IPTG induction.By measuring the activity of beta-lactamase activity (the  protocol has been described in detail in our note, please refer to it) after  induction and 21-hours culture, we obtained our expected tryptophan dependent  beta-lactamase activity increase with dynamic range up to 3mM tryptophan. <br />
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[[File:Sensor.jpg|446px|thumb|right]]
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<p align="center"><img border="0" width="446" src="/wiki/images/7/7d/Sensor.jpg" /> <br />
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  Aplasmid  used for performance test of our novel tryptophan sensor.
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   Figure.1 plasmid map for THU-E tryptophan-sensor part </p>
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   The sensor  was derived from one regulation sequence upstream of tryptophanase(tnaA) operon  in wild type <em>E. Coli</em><a href="#_ENREF_1" title="Gong, 2002 #484">3</a>. This sequence codesone 24-residue nascent peptide. Following  this nascent peptide sequence stands one transcription termination factor (Rho)  recognition sites. When certain amount of tryptophan exists, it is recognized  by the nascent peptide. This leads to the hindering of TnaC-peptidyl-tRNAPro  from being cleaved from ribosome. This peptide-mRNA-ribosome complex blocks Rho  factor’s access to its binding site which is just adjacent to termination codon  of nascent peptide so that initiate the transcription of downstream sequence. As  far as we know, this novel mechanism has not been utilized before as tryptophan  sensor.  
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   As a proof of  principle, we cloned beta-lactamase gene <em>lacZ</em> downstream of wild type nascent peptide and Rho interaction sequence. The  assembly was cloned between the NcoI and BamHI sites of pTrc99A vector with  IPTG induction.By measuring the activity of beta-lactamase activity (the  protocol has been described in detail in our note, please refer to it) after  induction and 21-hours culture, we obtained our expected tryptophan dependent  beta-lactamase activity increase with dynamic range up to 3mM tryptophan.  
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<p align="center"><img border="0" width="446" src="/wiki/images/a/a2/Part2II.png" /> <br />
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   Figure.1  Conception illustration of the working mechanism of novel tryptophan sensor
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<p align="center"><img border="0" width="446"  src="/wiki/images/e/ee/Part2I.png" /> <br />
<p align="center"><img border="0" width="446"  src="/wiki/images/e/ee/Part2I.png" /> <br />
   Figure.2 the performance of  tryptophan sensor measured by the dependent relation between tryptophan  concentration and beta-lactamase activity</p>
   Figure.2 the performance of  tryptophan sensor measured by the dependent relation between tryptophan  concentration and beta-lactamase activity</p>
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<p align="center"><img border="0" width="446" src="/wiki/images/a/a2/Part2II.png" /> <br />
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  Figure.3  Conception illustration of the working mechanism of novel tryptophan sensor </p>
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  3   <strong>Gong, F. &amp; Yanofsky, C. Instruction of  translating ribosome by nascent peptide. <em>Science</em> 297, 1864-1867, doi:10.1126/science.1073997 (2002).</strong></p>
  3   <strong>Gong, F. &amp; Yanofsky, C. Instruction of  translating ribosome by nascent peptide. <em>Science</em> 297, 1864-1867, doi:10.1126/science.1073997 (2002).</strong></p>

Revision as of 17:04, 23 September 2013

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4 2s.png
Part 2: THU-E Tryptophan-sensor Part

Sensor.jpg
Aplasmid  used for performance test of our novel tryptophan sensor.


 The sensor  was derived from one regulation sequence upstream of tryptophanase(tnaA) operon  in wild type E. Coli<a href="#_ENREF_1" title="Gong, 2002 #484">3</a>. This sequence codesone 24-residue nascent peptide. Following  this nascent peptide sequence stands one transcription termination factor (Rho)  recognition sites. When certain amount of tryptophan exists, it is recognized  by the nascent peptide. This leads to the hindering of TnaC-peptidyl-tRNAPro  from being cleaved from ribosome. This peptide-mRNA-ribosome complex blocks Rho  factor’s access to its binding site which is just adjacent to termination codon  of nascent peptide so that initiate the transcription of downstream sequence. As  far as we know, this novel mechanism has not been utilized before as tryptophan  sensor. 


 As a proof of  principle, we cloned beta-lactamase gene lacZ downstream of wild type nascent peptide and Rho interaction sequence. The  assembly was cloned between the NcoI and BamHI sites of pTrc99A vector with  IPTG induction.By measuring the activity of beta-lactamase activity (the  protocol has been described in detail in our note, please refer to it) after  induction and 21-hours culture, we obtained our expected tryptophan dependent  beta-lactamase activity increase with dynamic range up to 3mM tryptophan. 


Figure.1 Conception illustration of the working mechanism of novel tryptophan sensor


Figure.2 the performance of tryptophan sensor measured by the dependent relation between tryptophan concentration and beta-lactamase activity


3   Gong, F. & Yanofsky, C. Instruction of translating ribosome by nascent peptide. Science 297, 1864-1867, doi:10.1126/science.1073997 (2002).