View source for 8x9o


==Cte-U537ins-Branching,Ca,inactive==
<StructureSection load='8x9o' size='340' side='right'caption='[[8x9o]], [[Resolution|resolution]] 3.06&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[8x9o]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Comamonas_testosteroni_KF-1 Comamonas testosteroni KF-1]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=8X9O OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8X9O 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]] 3.06&#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>, <scene name='pdbligand=K:POTASSIUM+ION'>K</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=8x9o FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8x9o OCA], [https://pdbe.org/8x9o PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8x9o RCSB], [https://www.ebi.ac.uk/pdbsum/8x9o PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8x9o ProSAT]</span></td></tr>
</table>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Circularly permuted (CP) group II introns, identified in various bacteria phyla, swap domains D5 and D6 near the 5' end and have reversed splice sites (SSs), leading to backsplicing and circular RNA formation. In this study, we present multiple high-resolution cryo-electron microscopy structures of a natural CP group II intron from Comamonas testosteroni KF-1 (Cte 1), elucidating the molecular mechanisms of branching and backsplicing. During branching, the 5' SS is positioned by an auxiliary sequence (AUX)-enhanced interaction between the exon-binding site and intron-binding site (IBS) and stacks on the branch-site adenosine within D6, allowing the attacking 2'-OH group to coordinate with a metal ion in the active center. In backsplicing, the 3' SS is aligned with the branching step, leaving IBS in the active center, stabilized by base pairing with the AUX, which enables the free 3'-end hydroxyl group to directly attack the scissile phosphate of 3' SS. Furthermore, a groove in Cte 1 may stabilize the circular RNA. These findings highlight a conserved catalytic mechanism for canonical group II introns, albeit facilitated by the versatile AUX, opening avenues for designing potent ribozymes producing circular RNAs.

Structures of a natural circularly permuted group II intron reveal mechanisms of branching and backsplicing.,Ling X, Yao Y, Ma J Nat Struct Mol Biol. 2025 Feb 27. doi: 10.1038/s41594-025-01489-6. PMID:40016344<ref>PMID:40016344</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 8x9o" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Comamonas testosteroni KF-1]]
[[Category: Large Structures]]
[[Category: Ling XB]]
[[Category: Ma JB]]