Difference between revisions of "Team:UMaryland/Description"

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<p style = "font-size:18px" align = center><b>Hok: Small protein - Big effect</b></p>
 
<p style = "font-size:18px" align = center><b>Hok: Small protein - Big effect</b></p>
 
<p style="font-size:20px">In order to stay alive, cells need to be able to block translation of the hok transcript. Located on the same locus as hok is mok, which modulates whether or not hok is properly translated. Mok is located on a different reading frame than hok and the two genes are always co-transcribed as part of a single mRNA transcript.</p>
 
<p style="font-size:20px">In order to stay alive, cells need to be able to block translation of the hok transcript. Located on the same locus as hok is mok, which modulates whether or not hok is properly translated. Mok is located on a different reading frame than hok and the two genes are always co-transcribed as part of a single mRNA transcript.</p>
<p style="font-size:20px">Mok is then recognized by sok, a short ssRNA "antitoxin" transcribed on the reverse strand of the Hok-Sok cassette. Sok is capable of forming a double-stranded RNA duplex near the 5'-end of the mok transcript. This duplex formation indirectly blocks the hok open reading frame, preventing the transcript from being read. The dsRNA duplex is then recognized by RNAse III, leading to enzymatic degradation of the silenced transcript.</p>
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<p style="font-size:20px">Mok is then recognized by sok, a short ssRNA "antitoxin" transcribed under a strong constitutive promoter on the reverse strand of the Hok-Sok cassette. Sok is capable of forming a double-stranded RNA duplex near the 5'-end of the mok transcript. This duplex formation indirectly blocks the hok open reading frame, preventing the transcript from being read. The dsRNA duplex is then recognized by RNAse III, leading to enzymatic degradation of the silenced transcript.</p>
 
<p align = "center"><img src = "https://static.igem.org/mediawiki/2015/d/d0/RockEmUMD.png"></p>
 
<p align = "center"><img src = "https://static.igem.org/mediawiki/2015/d/d0/RockEmUMD.png"></p>
 
<p style = "font-size:18px" align = center><b>"Hok-Em, Sok-Em Robots"</b></p>
 
<p style = "font-size:18px" align = center><b>"Hok-Em, Sok-Em Robots"</b></p>
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</div>
 
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<p style="font-size:20px">How does this lead to plasmid maintenance? Hok mRNA, due to a high degree of secondary structure, has a long half-life, measured at 20 minutes. Sok, on the other hand, has a half-life of only 30 seconds. The cell must thus retain the coding region for Sok in order to produce enough Sok to continue blocking Hok translation. If the plasmid is lost, then both the Hok and Sok coding regions will be lost; however, previously transcribed Hok mRNA will still be present. With previously transcribed Sok rapidly degrading, Hok mRNA will be translated, killing the daughter cell that did not maintain the plasmid.
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<p style="font-size:20px">How does this process lead to plasmid maintenance? Hok mRNA, due to a high degree of secondary structure, has a long half-life, measured at 20 minutes. Sok, on the other hand, has a half-life of only 30 seconds. The cell must thus retain the plasmid, and thus, the coding region for Sok if it is to produce enough Sok to continue blocking Hok translation. If the plasmid is lost, then both the Hok and Sok coding regions will be lost; however, previously transcribed Hok mRNA will still be present. With previously transcribed Sok rapidly degrading, Hok mRNA will be translated, killing the daughter cell that did not maintain the plasmid.
  
 
<p style = "font-size:20px">Our wet project for 2015 was to demonstrate that the Hok-Sok system could maintain a plasmid over many generations as well as typical antibiotic maintenance systems. We hypothesized that the Hok-Sok system could thus serve as a cheap, ethical alternative to antibiotic pressure.</p>
 
<p style = "font-size:20px">Our wet project for 2015 was to demonstrate that the Hok-Sok system could maintain a plasmid over many generations as well as typical antibiotic maintenance systems. We hypothesized that the Hok-Sok system could thus serve as a cheap, ethical alternative to antibiotic pressure.</p>

Revision as of 18:27, 18 September 2015