View source for 3vnb


==Structural insights into small RNA sorting and mRNA binding by Arabidopsis Ago domains==
<StructureSection load='3vnb' size='340' side='right' caption='[[3vnb]], [[Resolution|resolution]] 1.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[3vnb]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Arath Arath]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3VNB OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3VNB FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[3vna|3vna]]</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3vnb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3vnb OCA], [http://pdbe.org/3vnb PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=3vnb RCSB], [http://www.ebi.ac.uk/pdbsum/3vnb PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=3vnb ProSAT]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/AGO1_ARATH AGO1_ARATH]] Involved in RNA-mediated post-transcriptional gene silencing (PTGS). Main component of the RNA-induced silencing complex (RISC) that binds to a short guide RNA such as microRNA (miRNA) or small interfering RNA (siRNA). RISC uses the mature miRNA or siRNA as a guide for slicer-directed cleavage of homologous mRNAs to repress gene expression. Requires DRB1 for directional loading of the small RNA duplex (guide stand and passenger strand) onto RISC for passenger strand degradation. Unlike animal RISC that associates in high molecular weight complex, Arabidopsis RISC is probably composed only of the AGO1 protein and associated RNA without any other proteins. Associates mainly with miRNAs of 21 nucleotide in length and preferentially recruits small RNAs with a 5' terminal uridine. Associates with 22 nucleotide miRNAs to trigger RDR6-dependent secondary siRNAs biogenesis. This pathway amplifies silencing by using the target RNA as substrate to generate secondary siRNAs. Binds to miR168 which targets its own mRNA for repression, establishing a homeostatic regulatory loop. Involved in antiviral RNA silencing by contributing to viral RNA clearance. Is capable of targeting viral RNAs with more compact structures than AGO7 which favors less structured RNA targets. May not associate with 24 nucleotide siRNAs involved in chromatin silencing. Essential for multiple processes in development. Essential for proper development of leaves and floral organs, and formation of axillary meristems. Like AGO10, required for stem cell function and organ polarity.<ref>PMID:9427751</ref> <ref>PMID:15882589</ref> <ref>PMID:16081530</ref> <ref>PMID:17158744</ref> <ref>PMID:18342361</ref> <ref>PMID:18342362</ref> <ref>PMID:18344228</ref> <ref>PMID:18799732</ref> <ref>PMID:20562854</ref> <ref>PMID:19763164</ref> <ref>PMID:19861421</ref>  
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== Publication Abstract from PubMed ==
The RISC-associated Argonaute (Ago) proteins play the catalytic role for RISC-mediated gene regulation by selecting small RNAs and subsequent targeting and cleavage of complementary mRNAs. Ago Mid domains are proposed to play essential roles in small RNA sorting. Here, we report the crystal structures of Arabidopsis Ago1 Mid domain and its chimera mutant with part of Ago1 replaced by Ago4. The structures demonstrate that a single amino insertion in the nucleotide specificity loop of AtAgo1 will change the nucleotide binding preference of AtAgo1 from "5'-U" to "5'-A". Moreover, we identify a long positively charged groove located along the "5'-end-nucleotide specificity loop" and occupied by several sulfate ions with the distance of 9-11A distance, indicating a putative mRNA target binding groove.

Structural insights into small RNA sorting and mRNA target binding by Arabidopsis Argonaute Mid domains.,Zha X, Xia Q, Adam Yuan Y FEBS Lett. 2012 Sep 21;586(19):3200-7. doi: 10.1016/j.febslet.2012.06.038. Epub, 2012 Jul 3. PMID:22771475<ref>PMID:22771475</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 3vnb" style="background-color:#fffaf0;"></div>

==See Also==
*[[Argonaute|Argonaute]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Arath]]
[[Category: Yuan, Y A]]
[[Category: Zha, X]]
[[Category: 5'-end nucleotide binding]]
[[Category: Rna binding protein]]
[[Category: Rossmann fold]]