ATP-bound states of GroEL captured by cryo-electron microscopy.
The chaperonin GroEL drives its protein-folding cycle by cooperatively binding ATP to one of its two rings, priming that ring to become folding-active upon GroES binding, while simultaneously discharging the previous folding chamber from the opposite ring. The GroEL-ATP structure, determined by cryo-EM and atomic structure fitting, shows that the intermediate domains rotate downward, switching their intersubunit salt bridge contacts from substrate binding to ATP binding domains. These observations, together with the effects of ATP binding to a GroEL-GroES-ADP complex, suggest structural models for the ATP-induced reduction in affinity for polypeptide and for cooperativity. The model for cooperativity, based on switching of intersubunit salt bridge interactions around the GroEL ring, may provide general insight into cooperativity in other ring complexes and molecular machines.
Ranson
N A
NA
Department of Crystallography, Birkbeck College London, Malet Street, London WC1E 7HX, United Kingdom. n.ranson@bbk.ac.uk
Farr
G W
GW
Roseman
A M
AM
Gowen
B
B
Fenton
W A
WA
Horwich
A L
AL
Saibil
H R
HR
D000255:Adenosine Triphosphate / Q000737:chemistry*; D018834:Chaperonin 60 / Q000737:chemistry* / Q000648:ultrastructure; D020285:Cryoelectron Microscopy; D004926:Escherichia coli; D008958:Models, Molecular; D011485:Protein Binding; D017510:Protein Folding
D018834:Chaperonin 60; D000255:Adenosine Triphosphate