View source for 9lgw


==Cryo-EM structure of SiAgo-Aga1 complex==
<StructureSection load='9lgw' size='340' side='right'caption='[[9lgw]], [[Resolution|resolution]] 2.70&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9lgw]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Sulfolobus_islandicus_M.16.4 Sulfolobus islandicus M.16.4]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9LGW OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9LGW 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]] 2.7&#8491;</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=9lgw FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9lgw OCA], [https://pdbe.org/9lgw PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9lgw RCSB], [https://www.ebi.ac.uk/pdbsum/9lgw PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9lgw ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/C4KI01_SULIK C4KI01_SULIK] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Prokaryotic Argonaute proteins (pAgos) defend the host against invading nucleic acids, including plasmids and viruses. Short pAgo systems confer immunity by inducing cell death upon detecting invading nucleic acids. However, the activation mechanism of the SiAgo system, comprising a short pAgo from the archaeon Sulfolobus islandicus and its associated proteins SiAga1 and SiAga2, remains largely unknown. Here, we determined the cryo-electron microscopy structures of the SiAgo-Aga1 apo complex and the RNA-DNA-bound SiAgo-Aga1 complex at resolutions of 2.7 and 3.0 A, respectively. Our results revealed that a positively charged pocket is generated from the interaction between SiAgo and SiAga1, exhibiting an architecture similar to APAZ-pAgo of short pAgo systems and accommodating the nucleic acids. Further investigation elucidated the conserved mechanism of nucleic acid recognition by SiAgo-Aga1. Both the SiAgo-Aga1 interaction and nucleic acid recognition by the complex are essential for antiviral defense. Biochemical and structural analyses demonstrated that SiAgo-Aga1 undergoes extensive conformational changes upon binding to the RNA-DNA duplex, thereby licensing its interaction with the effector SiAga2 to trigger the immune response. Overall, our findings highlight the evolutionary conservation of Agos across phylogenetic clades and provide structural insights into the activation mechanism of the SiAgo system.

Structural and mechanistic insights into the activation of a short prokaryotic argonaute system from archaeon Sulfolobus islandicus.,Dai Z, Chen Y, Guan Z, Chen X, Tan K, Yang K, Yan X, Liu Y, Gong Z, Han W, Zou T Nucleic Acids Res. 2025 Jan 24;53(3):gkaf059. doi: 10.1093/nar/gkaf059. PMID:39898546<ref>PMID:39898546</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 9lgw" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Sulfolobus islandicus M 16 4]]
[[Category: Dai ZK]]
[[Category: Guan ZY]]
[[Category: Zou TT]]