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- | <div class='content_1'><h3> Module Two what'sthename Description </h3> | + | |
- | <table class="content_table" align= "center" >
| + | <div class= "medal_text"> |
- |
| + | <h3 class= "What_medal"> Bronze Medal</h3> |
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| + | <ul> |
- | <td class= "content_cell" colspan= "2">
| + | <li>Lorem ipsum dolor sit amet, consectetuer adipiscing elit.</li> |
- | <div class= "content_area_one_row"> | + | <li>Aliquam tincidunt mauris eu risus.</li> |
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- | <p>Prof. Donald A. Morrison's research lab in University of Illinois at Chicago published several papers on the competence for genetic transformation
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- | in <i>Streptococcus pneumoniae</i> which depends on a quorum-sensing system to control many competence-specific genes which play a role in DNA uptake,
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- | processing, and integration. There is a link between this quorum-sensing system and the competence-specific genes, which is an alternative sigma
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- | factor ComX. Two identical copies of gene (<i>comX1</i> and <i>comX2</i>) encode a competence-specific alternative sigma factor, σ<sup>x</sup>.
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- | Expression of ComX allows the transcription of many genes that are involved in transformation and specifically expressed during competence. These late
| + | |
- | genes share a conserved 8-bp sequence in their promoter regions, TACGAATA (combox) which is specifically induced by σ<sup>x</sup>-containing
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- | RNA polymerase.
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- | </p> | + | |
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- | <p>The combox promoter is a promoter associated with initiating transcription of a class of genes (commonly referred to as late competence genes)
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- | coding for bacterial competence proteins and bacterial transformation in <i>Streptococcus Pneumoniae</i> strains. As described before, it contains
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- | a general consensus sequence of TACGAATA for recognition by its promoter-specific sigma factor X, which is a protein expressed from the early
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- | competence gene <i>comX</i>.
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- | </p>
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- | <p>In fact, the combox promoter can be found on many different regions within the genomic DNA of <i>Streptococcus
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- | Pneumoniae</i> strains. Researches and investigations have also reported variants of the combox promoter having different lengths and consensus
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- | sequences, but generally the range of variety has been kept small.
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- | </p>
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- | </tr>
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- | </table>
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| + | <div class= "medal_text "> |
- | <div class= "content_area_one_row"> | + | <h3 class= "What_medal"> Silver Medal</h3> |
- | <p>Though much information about the combox promoter is readily available nowadays, its full characterization including promoter activity, specificity, | + | <ul> |
- | sequence, as well as the biomolecular mechanism can be greatly enhanced with further investigations and experiments. As part of module II, we were
| + | <li>Lorem ipsum dolor sit amet, consectetuer adipiscing elit.</li> |
- | interested in reproducing this gene circuit with all the associated genes and promoters to be combined into a single transcriptional unit.
| + | <li>Aliquam tincidunt mauris eu risus.</li> |
- | To the best of our knowledge, the genes and promoters of this gene circuit for bacterial transformation are found at different locations of the
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- | long genomic DNA of many <i>Streptococcus Pneumoniae</i> strains. Despite the suggested susceptibility to leakage and other factors that may
| + | </ul> |
- | hinder or interrupt the mechanism, researches have reported that the pathway was highly specific to certain environmental conditions and stress, | + | |
- | suggesting minimal or no leakage in the entire process. With part I of module to focusing on ComX, part II of module II focused mainly on isolating
| + | |
- | the combox promoter, and also identifying the most probable length of the promoter. Characterization of the combox promoter was carried out
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- | together with the characterization of <i>comX</i> gene. Because combox promoter is highly specific to σ<sup>x</sup> for activation,
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- | genes downstream of the combox promoter will be translated only if σ<sup>x</sup> are present. Hence, by using fluorescence protein as a
| + | |
- | reporting mechanism, this <i>comX</i>-combox system could be further utilized as a specific reporter device that could be used by the iGEM
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- | community.
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- | </p> | + | |
| </div> | | </div> |
- | </td>
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- | <td class= "content_cell">
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- | <div class= "content_area_one_row">
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- | <img src= "https://static.igem.org/mediawiki/2014/thumb/b/bf/HKKUST_iGEM_2014_Pbad3d_graph_.png/180px-HKKUST_iGEM_2014_Pbad3d_graph_.png"/>
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- | </div>
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- | <br>
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- | <p> Besides ComX, another positive factor involved in competence regulation was later found out to be ComW. The <i>comW</i> gene (SP0018) is regulated
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- | by the quorum-sensing system and is required for a high-level of competence. Coexpression of <i>comW</i> with <i>comX </i>restores the
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- | accumulation of σ<sup>x</sup> and the expression of late genes as ComW contributes to the stabilization of the alternative sigma
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- | factor σ<sup>x</sup>against proteolysis and is required for full activity of σ<sup>x</sup> in directing transcription of late
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- | competence genes. ComW functions to act as a barrier which covers comX protein from being degraded by the ClpXP degradation enzyme. Hence, ComW
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- | will be degraded instead of ComX, and the production of ComX protein will be increased.
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- | </p>
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- | <br>
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- | <p>Based on these findings, we would like to integrate this alternative sigma factor system from Gram-positive <i>Streptococcus pneumoniae</i>
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- | into Gram-negative <i>Escherichia coli</i>. Firstly, we cloned out the <i>comX</i> and <i>comW</i> genes from the genomic DNA of <i>S. pneumoniae</i>
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- | NCTC 7465 strain. We then used BioBrick BBa_K880005 (consisting of constitutive promoter J23100 and strong RBS B0034) to drive the expression of those
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- | genes. Lastly, we combined these constructs with the combox promoter and GFP generator to check the functionality of the system, and to calculate the
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- | relative promoter unit of combox promoter.
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- | </p>
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- | </tr> | + | <div class= "each_medal"> |
- | </table>
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- |
| + | <div class= "medal_text "> |
- | <div class='content_1'>
| + | <h3 class= "What_medal"> Gold Medal</h3> |
- | <table class="content_table" align= "center" >
| + | <ul> |
- | <tr class= "content_row" >
| + | <li>Lorem ipsum dolor sit amet, consectetuer adipiscing elit.</li> |
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- | <p>
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- | <u>References</u>
| + | |
- | <br>
| + | |
- | <br>
| + | |
- | Andrew Piotrowski et al. (2009) "Competence for Genetic Transformation in <i>Streptococcus pneumoninae</i>: Termination of Activity of the Alternative Sigma Factor ComX Is Independent of Proteolysis of ComX and ComW" Journal of Bacteriology.
| + | |
- | <br>
| + | |
- | <br>
| + | |
- | Ping Luo et al. (2003) "Transient Association of an Alternative Sigma Factor, ComX, with RNA Polymerase during the Period of Competence for Genetic Transformation in <i>Streptococcus pneumonia</i>" Journal of Bacteriology.
| + | |
- | <br>
| + | |
- | <br>
| + | |
- | Sung CK et al. (2005) "Two distinct functions of ComW in stabilization and activation of the alternative sigma factor ComX in <i>Streptococcus pneumoniae</i>. " Journal of Bacteriology.
| + | |
- | <br>
| + | |
- | <br>
| + | |
- | Haiying Li et al. (2004) "Identification of ComW as a new component in regulation of genetic transformation in <i>Streptococcus Pneumoniae</i>" Molecular Biology.
| + | |
- | <br>
| + | |
- | <br>
| + | |
- | Myeong S.Lee et al. (1999) "Identification of a New Regulator in <i>Streptococcus Pneumoniae</i> Linking Quorum Sensing to Competence for Genetic Transformation"
| + | |
- | </p>
| + | |
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