View source for Featured Parts:RNA-Lock-and-Key

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===The Parts===
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<partinfo>J01008</partinfo> - ("key 1") Biobricked version of Isaacs' riboregulator trans activating key, taR12 <br>
<partinfo>J01010</partinfo> - ("lock 1") Biobricked version of Isaacs' riboregulator cis repressed lock, crR12. <br>
<partinfo>J01080</partinfo> - ("lock 3") Modified version of J01010 <br>
<partinfo>J01086</partinfo> - ("key 3") Modified version of J01008 <br>

===Background: How the Riboregulator Works===
This set of riboregulators are based upon the work of Isaacs et al 2004 (see reference #1).  They work by repressing the expression of a target gene by introducing a complementary region to prevent translation initiation.  <br>
The DNA sequences of the "locks" are modified directly upsteam of the target gene's ribosome binding site (RBS) such that the 5' untranslated region will fold to form a stem-loop secondary structure, thus blocking the RBS and preventing translation.  This stem-loop structure is known as the 'cis-repressed' mRNA (crRNA).  <br>
These "locked" stem-loops are 'unlocked' via what we call "keys".  These "keys" for non-coding RNA are called "trans-activating" RNA (taRNA).  They act to bind complementary regions within the lock to open the crRNA and allow proteins to bind at the RBS.

===Suggested Uses for these Biobricks===
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===Experimental and Technical===
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====Technical====
*crR12 ("lock1"): 
**Isaacs documentation (see reference #1): Sequence secondary structure forms a stem-loop with two dispersed "bulge" sites (formed by intentionally mismatched base pairings) which destabilize the stem-loop enough to allow the corresponding taR12 "key1" to interject itself and open the loop.

*taR12 ("key1"):
**Isaacs documentation (see reference #1): Under the induction of the araC promoter (using 0.25% arabinose solution), the taR12 key activated the corresponding crR12 lock to express the downstream indicator, GFP, to levels of flourescence 19-fold greater than without taR12 expression. Maximal expression was noted at 70 minutes after addition of arabinose solution, and was maintained after this point.

====Previous Experiments====
*taR12/crR12 (key1/lock1): For the gene sequence [araC][taR12][crR12][GFP], Activation of taR12 transcription induced by araC promoter unlocked the crR12 stem-loop enough to cause a 19-fold increase in GFP flourescence.  For more experiments see reference #1 Isaacs et al 2004.
*cross-talk: The cross talk between the two different pairs of locks and keys has not yet been tested.  Putatively, they should not interact but this has not yet been proven experimentally.

===References===
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*Publications on the Isaacs Riboregulator:
** Isaacs, Dwyer DJ, Ding C, Pervouchine DD, Cantor CR, Collins JJ. 2004. "Engineered riboregulators enable post-transcriptional control of gene expression". Nature Biotechnology 2004. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15208640&query_hl=7&itool=pubmed_docsum Pubmed] [http://www.nature.com/nbt/journal/v22/n7/abs/nbt986.html;jsessionid=ABB92F041E994E3B8E4A5213699C3CB0 Journal]

*More parts and resources
**A listing of more parts made by the Berkeley 2005 iGEM team including constituitively 'on' promoter-controlled riboregulators and other experimental constructs can be found [https://parts.igem.org/cgi/partsdb/pgroup.cgi?pgroup=iGEM&group=iGEM_Berkeley here]
**The second generation of riboregulators designed to optimize their specificity and efficiency are available from the [https://parts.igem.org/cgi/partsdb/pgroup.cgi?pgroup=iGEM2006&group=iGEM2006_Berkeley  Berkeley iGEM 2006 page.]