View source for 6kr6


==Crystal structure of Drosophila Piwi==
<StructureSection load='6kr6' size='340' side='right'caption='[[6kr6]], [[Resolution|resolution]] 2.90&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6kr6]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Drosophila_melanogaster Drosophila melanogaster]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6KR6 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6KR6 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]] 2.9&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=HG:MERCURY+(II)+ION'>HG</scene>, <scene name='pdbligand=N:ANY+5-MONOPHOSPHATE+NUCLEOTIDE'>N</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</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=6kr6 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6kr6 OCA], [https://pdbe.org/6kr6 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6kr6 RCSB], [https://www.ebi.ac.uk/pdbsum/6kr6 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6kr6 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/PIWI_DROME PIWI_DROME] Acts via the piwi-interacting RNA (piRNA) metabolic process, which mediates the repression of transposable elements during meiosis by forming complexes composed of piRNAs and Piwi proteins and governs the methylation and subsequent repression of transposons (PubMed:26808625, PubMed:15817569, PubMed:17346786). Directly binds piRNAs, a class of 24 to 30 nucleotide RNAs that are generated by a Dicer-independent mechanism and are primarily derived from transposons and other repeated sequence elements (PubMed:16882972). In ovarian somatic cells, mediates silencing of transposable elements at the transcriptional level in a mael-dependent manner (PubMed:23159368, PubMed:28472469). Involved in silencing of long terminal repeat (LTR) retrotransposons in male germline (PubMed:15817569). In testis, regulates spermatogenesis together with Tudor-SN (PubMed:26808625). In germ cells, mediates silencing at both transcriptional and post-transcriptional levels and is involved in the maintenance of populations of primary and secondary piRNAs. Piwi-mediated transcriptional silencing is accompanied by the formation of His3 'Lys-9' trimethylated (H3K9me3) euchromatin and heterochromatin (PubMed:23434410, PubMed:23392610). In ovary, associates predominantly with antisense piRNAs that contain uridine at their 5' end. Association with sense piRNAs is also observed but to a lesser extent. Mediates a somatic signaling mechanism required for the maintenance of germline stem cells to produce and maintain a daughter germline stem cell (PubMed:9851978, PubMed:10631171, PubMed:9199372, PubMed:16949822). It is not essential for the further differentiation of the committed daughter cell (PubMed:9851978). Acts cell autonomously to promote germline stem cell division (PubMed:9851978, PubMed:10631171). Its role in stem cell maintenance does not seem to require nuclear localization. Required maternally for the posterior localization of osk and vas and for pole cell formation during oogenesis and early embryogenesis (PubMed:16949822). Together with Hop and Hsp83, mediates canalization, also known as developmental robustness, likely via epigenetic silencing of existing genetic variants and suppression of transposon-induced new genetic variation (PubMed:21186352). Shows RNA cleavage activity, although is not required for any of its known functions (PubMed:9199372, PubMed:16882972, PubMed:23297219).<ref>PMID:10631171</ref> <ref>PMID:15817569</ref> <ref>PMID:16882972</ref> <ref>PMID:16949822</ref> <ref>PMID:17346786</ref> <ref>PMID:17875665</ref> <ref>PMID:17952056</ref> <ref>PMID:20966047</ref> <ref>PMID:21186352</ref> <ref>PMID:22065765</ref> <ref>PMID:23159368</ref> <ref>PMID:23297219</ref> <ref>PMID:23392609</ref> <ref>PMID:23392610</ref> <ref>PMID:23434410</ref> <ref>PMID:26808625</ref> <ref>PMID:28472469</ref> <ref>PMID:9199372</ref> <ref>PMID:9851978</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
PIWI-clade Argonaute proteins associate with PIWI-interacting RNAs (piRNAs), and silence transposons in animal gonads. Here, we report the crystal structure of the Drosophila PIWI-clade Argonaute Piwi in complex with endogenous piRNAs, at 2.9 A resolution. A structural comparison of Piwi with other Argonautes highlights the PIWI-specific structural features, such as the overall domain arrangement and metal-dependent piRNA recognition. Our structural and biochemical data reveal that, unlike other Argonautes including silkworm Siwi, Piwi has a non-canonical DVDK tetrad and lacks the RNA-guided RNA cleaving slicer activity. Furthermore, we find that the Piwi mutant with the canonical DEDH catalytic tetrad exhibits the slicer activity and readily dissociates from less complementary RNA targets after the slicer-mediated cleavage, suggesting that the slicer activity could compromise the Piwi-mediated co-transcriptional silencing. We thus propose that Piwi lost the slicer activity during evolution to serve as an RNA-guided RNA-binding platform, thereby ensuring faithful co-transcriptional silencing of transposons.

Crystal structure of Drosophila Piwi.,Yamaguchi S, Oe A, Nishida KM, Yamashita K, Kajiya A, Hirano S, Matsumoto N, Dohmae N, Ishitani R, Saito K, Siomi H, Nishimasu H, Siomi MC, Nureki O Nat Commun. 2020 Feb 12;11(1):858. doi: 10.1038/s41467-020-14687-1. PMID:32051406<ref>PMID:32051406</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6kr6" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Drosophila melanogaster]]
[[Category: Large Structures]]
[[Category: Hirano S]]
[[Category: Ishitani R]]
[[Category: Mastumoto N]]
[[Category: Nishimasu H]]
[[Category: Nureki O]]
[[Category: Oe A]]
[[Category: Yamaguchi S]]
[[Category: Yamashita K]]