Difference between revisions of "SHAPE"

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<p>=== Data processing ===</p>
<p>=== Data processing ===</p>
<p style="padding-left: 30px;"><em>possible reference for this paragraph:&nbsp;http://rnajournal.cshlp.org/content/17/9/1688.full.pdf section "Data processing"</em></p>
<p style="padding-left: 30px;"><em>possible reference for this paragraph:&nbsp;http://rnajournal.cshlp.org/content/17/9/1688.full.pdf section "Data processing"</em></p>
<p>== A more detailed explanation of the SHAPE process ==</p>
<p>== To be incorporated ==</p>
<p>[[File:SHAPE reaction.png|thumb|400px]]This chemical probing strategy assesses local flexibility in [[RNA]] via accessibility of the [[ribose]] 2&prime;-OH group to acylation by the electrophilic reagent NMIA or [[1M7]]. In flexible regions (such as [[loop]]s, [[bulge]]s, and [[junction]]s), RNA adopts conformations that will promote formation of a nucleophilic 2&prime;-oxyanion which reacts with NMIA or 1M7 to form a bulky 2&prime;-O-adduct. Modified RNAs are subsequently evaluated by primer extension with an [[RNase]] H-deficient reverse transcriptase, creating a [[cDNA]] library corresponding to stops at sites of adduct formation in the RNA.</p>
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<p>== External links ==</p>
<p>== External links ==</p>

Revision as of 20:13, 6 March 2014

The SHAPE acronym stands for "Selective 2′ hydroxyl acylation analyzed by primer extension". It is the primary method used to evaluate designs in EteRNA lab experiments.


Warning: this page is under heavy construction. The material is being accumulated, before it is refined. You are (very) welcome to participate.





Experimental methods exist for determining, at the level of individual atoms, the various inter-atomic bindings that determine how an RNA molecule folds.  However, this type of experiment can take months to perform, for a single RNA sequence.  The EteRNA cloud lab process is now synthesizing more than 1000 novel RNA molecules per month, and as players/scientists, we expect the results for all 1000 sequences to be available in weeks, if not days.  To meet this need, the EteRNA biochemistry team is pioneering the development of high-throughput RNA analysis, and well as high-throughput RNA synthesis.  This high-throuhput analysis is under continual development and evolution, and improvements are continally being introduced into the EteRNA cloud labs.  EteRNA players who participate in the cloud labs and question the results that get back are actually part of the scientific review process.

At a very high level of abstraction, SHAPE analysis works by mixing a chemical reagent (e.g. 1M7), called the SHAPE probe, into a solution containing many thousands of copies of each distinct RNA molecule being analyzed. The SHAPE probe has the potential for chemically attacking and modifying every base of every RNA in the solution. However, the speed with which the probe modifies the individual bases varies over several orders of magnitude.  By carefully controlling the time of the exposure, the SHAPE procedure can limit the reaction so that only a small percentage of all the bases are modified.  Using modern technology for processing nucleic acid chains, the number of times any analogous base has been modified can be counted, and the base-probe reaction rate for each base position of each distinct RNA moleculte can be estimated.

This base-probe reaction rate is not a direct measurement of whether the base is or is not bound to a complementary base via one of the three pair bonds recognized in EteRNA puzzles -- CG, AU and GU. It's not even known exactly what details of a base's configuration goes into determning the reaction rate.  But the general consensus is that the reaction rate is an indication of how flexible the RNA's backbone is at each base position.  This flexibility is highly correlated with (but not wholly determined by) whether or not the base is paired to one of its complements (C with G, G with either C or U, etc).  This high correlation is the justification for using the SHAPE data as a measure of whether or not the base is bound, for the purpose of assigning the "score" for the molecule.  But the fact that it is not a perfect correlation ensures that there will be an ongoing discussion among the most engaged players and the EteRNA scientists about how the SHAPE data should be presented and interpreted.

Background: The high-level structure of RNA


Background: Laboratory procedures

It would seem that nearly everything we want to know about Cloud Lab procedures is described in http://arxiv.org/pdf/1304.1072.pdf


Teaching about PCR

Transcription (DNA to RNA)

Here's a short video on transcription in the living cell, emphasizing how rapidly it occurs.


Chemical modification

Looks like a good figure, covering chemical mod and RT

Reverse transcription (RNA to DNA)

Data collection (Gel / Capillary Electrophoresis)

Data processing

possible reference for this paragraph: http://rnajournal.cshlp.org/content/17/9/1688.full.pdf section "Data processing"

External links

Personal tools
Main page
Introduction to the Game