View source for 9qcc


==Activated XauSPARDA filament assembly with bound dsDNA substrate==
<StructureSection load='9qcc' size='340' side='right'caption='[[9qcc]], [[Resolution|resolution]] 3.00&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9qcc]] is a 34 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] and [https://en.wikipedia.org/wiki/Xanthobacter_autotrophicus_Py2 Xanthobacter autotrophicus Py2]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9QCC OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9QCC 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&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</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=9qcc FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9qcc OCA], [https://pdbe.org/9qcc PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9qcc RCSB], [https://www.ebi.ac.uk/pdbsum/9qcc PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9qcc ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/A7ICE8_XANP2 A7ICE8_XANP2] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Present in all three domains of life, Argonaute proteins use short oligonucleotides as guides to recognize complementary nucleic acid targets. In eukaryotes, Argonautes are involved in RNA silencing, whereas in prokaryotes, they function in host defense against invading DNA. Here, we show that SPARDA (short prokaryotic Argonaute, DNase associated) systems from Xanthobacter autotrophicus (Xau) and Enhydrobacter aerosaccus (Eae) function in anti-plasmid defense. Upon activation, SPARDA nonspecifically degrades both invader and genomic DNA, causing host death, thereby preventing further spread of the invader in the population. X-ray structures of the apo Xau and EaeSPARDA complexes show that they are dimers, unlike other apo short pAgo systems, which are monomers. We show that dimerization in the apo state is essential for inhibition of XauSPARDA activity. We demonstrate by cryo-EM that activated XauSPARDA forms a filament. Upon activation, the recognition signal of the bound guide/target duplex is relayed to other functional XauSPARDA sites through a structural region that we termed the "beta-relay". Owing to dramatic conformational changes associated with guide/target binding, XauSPARDA undergoes a "dimer-monomer-filament" transition as the apo dimer dissociates into the guide/target-loaded monomers that subsequently assemble into the filament. Within the activated filament, the DREN nuclease domains form tetramers that are poised to cleave dsDNA. We show that other SPARDAs also form filaments during activation. Furthermore, we identify the presence of the beta-relay in pAgo from all clades, providing new insights into the structural mechanisms of pAgo proteins. Taken together, these findings reveal the detailed structural mechanism of SPARDA and highlight the importance of the beta-relay mechanism in signal transduction in Argonautes.

Activation of the SPARDA defense system by filament assembly using a beta-relay signaling mechanism widespread in prokaryotic Argonautes.,Jurgelaitis E, Zagorskaite E, Kopustas A, Asmontas S, Manakova E, Dalgediene I, Tylenyte U, Silanskas A, Toliusis P, Grybauskas A, Tutkus M, Venclovas C, Zaremba M Cell Res. 2025 Dec;35(12):1056-1078. doi: 10.1038/s41422-025-01198-1. Epub 2025 , Nov 27. PMID:41298897<ref>PMID:41298897</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 9qcc" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Large Structures]]
[[Category: Xanthobacter autotrophicus Py2]]
[[Category: Jurgelaitis E]]
[[Category: Manakova EN]]
[[Category: Zaremba M]]