PDBsum entry 4ab3

Chaperone

PDB id: 4ab3

Contents

Protein chains

(+ 8 more) 524 a.a.

Ligands

PO4 ×14

ATP ×14

Metals

_MG ×14

References listed in PDB file

Key reference

• Title: Atp-Triggered conformational changes delineate substrate-Binding and -Folding mechanics of the groel chaperonin.
• Authors: D.K.Clare, D.Vasishtan, S.Stagg, J.Quispe, G.W.Farr, M.Topf, A.L.Horwich, H.R.Saibil.
• Ref.: Cell, 2012, 149, 113-123.
• PubMed id: 22445172

Abstract

The chaperonin GroEL assists the folding of nascent or stress-denatured polypeptides by actions of binding and encapsulation. ATP binding initiates a series of conformational changes triggering the association of the cochaperonin GroES, followed by further large movements that eject the substrate polypeptide from hydrophobic binding sites into a GroES-capped, hydrophilic folding chamber. We used cryo-electron microscopy, statistical analysis, and flexible fitting to resolve a set of distinct GroEL-ATP conformations that can be ordered into a trajectory of domain rotation and elevation. The initial conformations are likely to be the ones that capture polypeptide substrate. Then the binding domains extend radially to separate from each other but maintain their binding surfaces facing the cavity, potentially exerting mechanical force upon kinetically trapped, misfolded substrates. The extended conformation also provides a potential docking site for GroES, to trigger the final, 100° domain rotation constituting the "power stroke" that ejects substrate into the folding chamber.