Difference between revisions of "Help:Terminators"
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[[Image:Part icon terminator.png]]
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[[Category:Terminators]]
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<small>
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[[Terminators|< Back to Terminators]]
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Browse [https://parts.igem.org/cgi/partsdb/pgroup.cgi?pgroup=terminator terminator parts]!</small>
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<hr>
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A terminator (short for "transcriptional terminator") is a stretch of DNA which halts the process of transcription (copying the DNA sequence into RNA). 
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{{:Terminators/Overview}}
  
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*[[Help:Terminators/Mechanism|'''How''']] do terminators work?
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==Stem-loop type terminators==
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*[[Help:Terminators/Glossary|'''Glossary''']] of terms relating to terminators
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[[Image:B0011 - stem loop terminator.png|thumb|An example of a stem-loop coding region (location indicated by the hairpin picture) in [[Part:BBa_B0011]]]]
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*[[Help:Terminators/Design|'''How to design a terminator''']]
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In our prokaryotic biobricks, [https://parts.igem.org/cgi/partsdb/pgroup.cgi?pgroup=cell host cells], these [https://parts.igem.org/cgi/partsdb/pgroup.cgi?pgroup=terminator terminator parts] are often palindromic (same sequence backwards and forwards) and form a stem-loop structure by folding back on itself and terminates transcription in this way.<br>
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*[[Help:Terminators/Construction|'''How to construct an terminator''']]
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One example of a biobrick which uses this method is the terminator [[Part:BBa_B0011]], which has the palindromic sequence "<font color = "green">aaaagccagattat</font><font color = "red">taatccggctttt</font>"
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*[[Help:Terminators/Measurement|'''How termination efficiencies are measured''']]
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*[[Help:Terminators/Further reading|'''Further reading''']] about terminator sequence and function
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==Poly-A tails==
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*[[Terminators/Catalog|'''Browse''']] the terminator parts available from the registry
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In eukaryotic hosts such as [https://parts.igem.org/wiki/index.php/Yeast yeast], a string of adenosine ("A") nucleotides is the primary method through which termination of transcription occurs.  This is mediated by exonucleases (enzymes which cut at this recognition sequence).  A popular "poly-A" motif is "<b>AAUAAA</b>".
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==Rho type terminators==
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Another method which cells use to terminate a sequence is through the action of the Rho protein.
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Latest revision as of 21:41, 20 July 2017

< Back to Terminators

A rho-independent transcriptional terminator. Image courtesy of Kingsford et al..

Terminators are genetic parts that usually occur at the end of a gene or operon and cause transcription to stop. In prokaryotes, terminators usually fall into two categories (1) rho-independent terminators and (2) rho-dependent terminators.

Rho-independent terminators are generally composed of palindromic sequence that forms a stem loop rich in G-C base pairs followed by several T bases. The conventional model of transcriptional termination is that the stem loop causes RNA polymerase to pause and transcription of the poly-A tail causes the RNA:DNA duplex to unwind and dissociate from RNA polymerase.

All the E. coli terminators in the Registry are rho-independent terminators. Rho-dependent terminators are not included, because rho-dependent terminators are not specified by sequence.