CRYSTAL STRUCTURE OF THE ASYMMETRIC CHAPERONIN COMPLEX GROEL/GROES/(ADP)7
[CH60_ECOLI] Prevents misfolding and promotes the refolding and proper assembly of unfolded polypeptides generated under stress conditions.[HAMAP-Rule:MF_00600] Essential for the growth of the bacteria and the assembly of several bacteriophages. Also plays a role in coupling between replication of the F plasmid and cell division of the cell.[HAMAP-Rule:MF_00600] [CH10_ECOLI] Binds to Cpn60 in the presence of Mg-ATP and suppresses the ATPase activity of the latter.[HAMAP-Rule:MF_00580]
Publication Abstract from PubMed
Chaperonins assist protein folding with the consumption of ATP. They exist as multi-subunit protein assemblies comprising rings of subunits stacked back to back. In Escherichia coli, asymmetric intermediates of GroEL are formed with the co-chaperonin GroES and nucleotides bound only to one of the seven-subunit rings (the cis ring) and not to the opposing ring (the trans ring). The structure of the GroEL-GroES-(ADP)7 complex reveals how large en bloc movements of the cis ring's intermediate and apical domains enable bound GroES to stabilize a folding chamber with ADP confined to the cis ring. Elevation and twist of the apical domains double the volume of the central cavity and bury hydrophobic peptide-binding residues in the interface with GroES, as well as between GroEL subunits, leaving a hydrophilic cavity lining that is conducive to protein folding. An inward tilt of the cis equatorial domain causes an outward tilt in the trans ring that opposes the binding of a second GroES. When combined with new functional results, this negative allosteric mechanism suggests a model for an ATP-driven folding cycle that requires a double toroid.
The crystal structure of the asymmetric GroEL-GroES-(ADP)7 chaperonin complex.,Xu Z, Horwich AL, Sigler PB Nature. 1997 Aug 21;388(6644):741-50. PMID:9285585
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.