View source for 9i23


==Structure of Human helicase RecQ1- 795-2T G-quadruplex - ADP complex==
<StructureSection load='9i23' size='340' side='right'caption='[[9i23]], [[Resolution|resolution]] 3.69&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9i23]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9I23 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9I23 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]] 3.69&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ADP:ADENOSINE-5-DIPHOSPHATE'>ADP</scene>, <scene name='pdbligand=K:POTASSIUM+ION'>K</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</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=9i23 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9i23 OCA], [https://pdbe.org/9i23 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9i23 RCSB], [https://www.ebi.ac.uk/pdbsum/9i23 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9i23 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/RECQ1_HUMAN RECQ1_HUMAN] DNA helicase that may play a role in the repair of DNA that is damaged by ultraviolet light or other mutagens. Exhibits a magnesium-dependent ATP-dependent DNA-helicase activity that unwinds single- and double-stranded DNA in a 3'-5' direction.<ref>PMID:15886194</ref> <ref>PMID:7961977</ref> <ref>PMID:8056767</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
RECQ1, the most abundant RecQ helicase in human cells, is involved in telomere maintenance in ALT cells and plays a critical role in maintaining genomic integrity and stability. Here, we present five high-resolution crystal structures that systematically reveal a novel mechanism by which the RECQ1 helicase recognizes and regulates G-quadruplex (G4) DNA structures. Our results demonstrate that DNA binding induces intra-subunit rearrangement in RECQ1, transitioning it from a closed to an open conformation. This rearrangement alters the stability of the dimer interface. G4 recognition and unwinding are driven by coordinated interactions between the D1/D2 domains and the single-stranded DNA (ssDNA)-binding channel. This dual engagement aligns the G4 tetrad in a geometry favorable for unwinding. ATP hydrolysis facilitates ssDNA translocation, positioning the beta-hairpin to disrupt hydrogen bonds-unraveling G4 structures in a manner analogous to the unwinding of dsDNA. This study proposes a mechanistic model for RECQ1-mediated G4 unwinding and elucidates how RECQ1 recognizes and unwinds distinct DNA structures.

Structural mechanism of RECQ1 helicase in unfolding G-quadruplexes compared with duplex DNA.,Song ZY, Zhang X, Ai X, Huang LY, Hou XM, Fosse P, Liu NN, Mauffret O, Rety S, Xi XG Nucleic Acids Res. 2025 Sep 5;53(17):gkaf877. doi: 10.1093/nar/gkaf877. PMID:40966504<ref>PMID:40966504</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 9i23" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Ai X]]
[[Category: Liu NN]]
[[Category: Rety S]]
[[Category: Song ZY]]
[[Category: Xi XG]]