View source for 3cun


==Aminoacyl-tRNA synthetase ribozyme==
<StructureSection load='3cun' size='340' side='right'caption='[[3cun]], [[Resolution|resolution]] 3.00&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[3cun]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3CUN OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3CUN FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 3&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CO:COBALT+(II)+ION'>CO</scene>, <scene name='pdbligand=GTP:GUANOSINE-5-TRIPHOSPHATE'>GTP</scene>, <scene name='pdbligand=K:POTASSIUM+ION'>K</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=MSE:SELENOMETHIONINE'>MSE</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=3cun FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3cun OCA], [https://pdbe.org/3cun PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3cun RCSB], [https://www.ebi.ac.uk/pdbsum/3cun PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3cun ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/SNRPA_HUMAN SNRPA_HUMAN] Binds stem loop II of U1 snRNA. It is the first snRNP to interact with pre-mRNA. This interaction is required for the subsequent binding of U2 snRNP and the U4/U6/U5 tri-snRNP. In a snRNP-free form (SF-A) may be involved in coupled pre-mRNA splicing and polyadenylation process. Binds preferentially to the 5'-UGCAC-3' motif in vitro.<ref>PMID:9848648</ref> 
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/cu/3cun_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=3cun ConSurf].
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== Publication Abstract from PubMed ==
In modern organisms, protein enzymes are solely responsible for the aminoacylation of transfer RNA. However, the evolution of protein synthesis in the RNA world required RNAs capable of catalysing this reaction. Ribozymes that aminoacylate RNA by using activated amino acids have been discovered through selection in vitro. Flexizyme is a 45-nucleotide ribozyme capable of charging tRNA in trans with various activated l-phenylalanine derivatives. In addition to a more than 10(5) rate enhancement and more than 10(4)-fold discrimination against some non-cognate amino acids, this ribozyme achieves good regioselectivity: of all the hydroxyl groups of a tRNA, it exclusively aminoacylates the terminal 3'-OH. Here we report the 2.8-A resolution structure of flexizyme fused to a substrate RNA. Together with randomization of ribozyme core residues and reselection, this structure shows that very few nucleotides are needed for the aminoacylation of specific tRNAs. Although it primarily recognizes tRNA through base-pairing with the CCA terminus of the tRNA molecule, flexizyme makes numerous local interactions to position the acceptor end of tRNA precisely. A comparison of two crystallographically independent flexizyme conformations, only one of which appears capable of binding activated phenylalanine, suggests that this ribozyme may achieve enhanced specificity by coupling active-site folding to tRNA docking. Such a mechanism would be reminiscent of the mutually induced fit of tRNA and protein employed by some aminoacyl-tRNA synthetases to increase specificity.

Structural basis of specific tRNA aminoacylation by a small in vitro selected ribozyme.,Xiao H, Murakami H, Suga H, Ferre-D'Amare AR Nature. 2008 Jul 17;454(7202):358-61. Epub 2008 Jun 11. PMID:18548004<ref>PMID:18548004</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 3cun" style="background-color:#fffaf0;"></div>

==See Also==
*[[Nucleoprotein 3D structures|Nucleoprotein 3D structures]]
*[[Ribozyme 3D structures|Ribozyme 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Ferre-D'Amare AR]]
[[Category: Murakami H]]
[[Category: Suga H]]
[[Category: Xiao H]]