View source for 8sp3


==Asymmetric dimer of MapSPARTA bound with gRNA/tDNA hybrid==
<StructureSection load='8sp3' size='340' side='right'caption='[[8sp3]], [[Resolution|resolution]] 3.52&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[8sp3]] is a 8 chain structure with sequence from [https://en.wikipedia.org/wiki/Maribacter_polysiphoniae Maribacter polysiphoniae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=8SP3 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8SP3 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 3.52&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MG:MAGNESIUM+ION'>MG</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=8sp3 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8sp3 OCA], [https://pdbe.org/8sp3 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8sp3 RCSB], [https://www.ebi.ac.uk/pdbsum/8sp3 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8sp3 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/A0A316E683_9FLAO A0A316E683_9FLAO] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
While eukaryotic Argonautes and long prokaryotic Argonautes (pAgos) cleave nucleic acids, some short pAgos lack nuclease activity and hydrolyze NAD(P)(+) to induce bacterial cell death(1). We present a hierarchical activation pathway for SPARTA, a short pAgo consisting of an Ago protein and an associated protein TIR-APAZ(2). SPARTA progresses through distinct oligomeric forms, including a monomeric apo state, a monomeric RNA/DNA-bound state, two dimeric RNA/DNA-bound states, and a tetrameric RNA/DNA-bound active state. These snapshots together identify oligomerization as a mechanistic principle of SPARTA activation. Apo SPARTA is inactive, its RNA/DNA-binding channel occupied an auto-inhibitory motif in TIR-APAZ. Upon RNA/DNA binding, SPARTA transitions from a monomer to a symmetric and then an asymmetric dimer, in which two TIR domains interact via charge and shape complementarity. Next, two dimers assemble into a tetramer with a central TIR cluster responsible for hydrolyzing NAD(P)(+). Additionally, we observed unique features of SPARTA-RNA/DNA interactions, including competition between the DNA 3' end and the auto-inhibitory motif, interactions between the RNA G2 nucleotide and Ago, and splaying of the RNA-DNA duplex by two loops exclusive to short pAgos. Together, our findings contribute a mechanistic basis for the activation of short pAgos, a large section of the Ago superfamily.

Oligomerization-mediated activation of a short prokaryotic Argonaute.,Shen Z, Yang XY, Xia S, Huang W, Taylor DJ, Nakanishi K, Fu TM Nature. 2023 Jul 26. doi: 10.1038/s41586-023-06456-z. PMID:37494956<ref>PMID:37494956</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 8sp3" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Maribacter polysiphoniae]]
[[Category: Fu TM]]
[[Category: Shen ZF]]
[[Category: Yang XY]]