View source for 9si0


==Cryo-EM structure of the catalytic core of human telomerase at the pre-termination state of the repeat addition cycle==
<StructureSection load='9si0' size='340' side='right'caption='[[9si0]], [[Resolution|resolution]] 3.80&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9si0]] is a 6 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=9SI0 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9SI0 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]] 3.8&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=1GC:2-DEOXY-5-O-[(R)-HYDROXY{[(S)-HYDROXY(PHOSPHONOOXY)PHOSPHORYL]METHYL}PHOSPHORYL]GUANOSINE'>1GC</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=9si0 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9si0 OCA], [https://pdbe.org/9si0 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9si0 RCSB], [https://www.ebi.ac.uk/pdbsum/9si0 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9si0 ProSAT]</span></td></tr>
</table>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
In most eukaryotes, the reverse transcriptase telomerase counteracts telomere shortening by processively adding telomeric DNA repeat sequences to chromosome ends. Telomerase activity depends on the telomerase reverse transcriptase (TERT) and the telomerase RNA (hTR in humans). Processive telomere elongation is critical for genome stability, and defects in this mechanism are linked to cellular dysfunction and human disease. However, the structural basis for telomerase repeat addition processivity in humans has remained elusive. Here, we present cryo-electron microscopy structures of human telomerase bound to telomeric DNA and an incoming nucleotide, captured at three distinct stages of its repeat addition cycle: initiation, elongation, and pre-termination. Across these states, the TERT active site maintains a conserved architecture that stabilises a short DNA-RNA duplex of constant length of four base-pairs. Beyond the active site, we identify dynamic structural features in both TERT and hTR that facilitate substrate engagement and RNA template repositioning, thereby supporting the synthesis of successive telomeric repeats. Together, these structures provide key insights into how human telomerase achieves its unique processivity to maintain telomere length and genome integrity.

Structures of nucleotide-bound human telomerase at several steps of its telomeric DNA repeat addition cycle.,Balch S, Franco-Echevarria E, Ghanim GE, Kretsch RC, Das R, Nguyen THD Nat Commun. 2026 Jan 21. doi: 10.1038/s41467-026-68560-8. PMID:41565648<ref>PMID:41565648</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 9si0" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Balch S]]
[[Category: Das R]]
[[Category: Franco-Echevarria E]]
[[Category: Ghanim GE]]
[[Category: Kretsch RC]]
[[Category: Nguyen THD]]