View source for 9rwq


==Ancestral Group III Chaperonin (ACIII) Double-Ring in Open Conformation including the Equatorial and Intermediate Domains (residues 12-200 and 356-507)==
<StructureSection load='9rwq' size='340' side='right'caption='[[9rwq]], [[Resolution|resolution]] 3.21&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9rwq]] is a 16 chain structure with sequence from [https://en.wikipedia.org/wiki/Synthetic_construct Synthetic construct]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9RWQ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9RWQ 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]] 3.21&#8491;</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=9rwq FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9rwq OCA], [https://pdbe.org/9rwq PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9rwq RCSB], [https://www.ebi.ac.uk/pdbsum/9rwq PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9rwq ProSAT]</span></td></tr>
</table>
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== Publication Abstract from PubMed ==
Chaperonins are essential protein-folding machines, classified into three structural and phylogenetic groups: Group I (bacterial GroEL), Group II (archaeal thermosome and eukaryotic CCT), and Group III (bacterial thermosome-like). Using ancestral sequence reconstruction (ASR) and protein resurrection, we inferred and experimentally characterized the last common ancestors of these groups (Ancestral Chaperonins ACI, ACII, and ACIII). The resurrected proteins exhibited ATPase activity (except ACII) and protected client proteins from heat-induced inactivation. Structural analyses by electron microscopy and Cryo-EM revealed that ACI forms single 7-mer rings, whereas ACII adopts a mixed population of single/double 8-mer rings, representing the first experimental observation of intermediate oligomeric states. ACII also features a unique cochaperonin-independent closure mechanism, distinct from modern Group I and II chaperonins. Together, these findings provide the experimental structural reconstruction of the most ancient and complex multimeric proteins so far, uncover novel intermediate states in chaperonin evolution, and offer a direct empirical framework for studying the emergence of multimeric complexity in early cellular life.

Ancestral Chaperonins Provide the First Structural Glimpse into Early Multimeric Protein Evolution.,Severino R, Cuellar J, Gutierrez-Seijo J, Maestro-Lopez M, Sanchez-Pulido L, Santiago C, Moreno-Paz M, Valpuesta JM, Parro V Mol Biol Evol. 2025 Nov 28:msaf314. doi: 10.1093/molbev/msaf314. PMID:41310978<ref>PMID:41310978</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Synthetic construct]]
[[Category: Cuellar J]]
[[Category: Gutierrez-Seijo J]]
[[Category: Severino R]]