The protein-folding activity of chaperonins correlates with the symmetric GroEL(14)(GroES(7))(2) heterooligomer

Chaperonins GroEL and GroES form, in the presence of ATP, two types of heterooligomers in solution: an asymmetric GroEL(14)GroES(7) ''bullet''-shaped particle and a symmetric GroEL(14)(GroES(7))(2) ''football''-Shaped particle. Under limiting concentrations of ATP or GroES, excess ADP, or in the presence of 5'-adenylyl imidodiphosphate, a correlation is seen between protein folding and the amount of symmetric GroEL(14)(GroES(7))(2) particles in a chaperonin solution, as detected by electron microscopy or by chemical crosslinking. kinetic analysis suggests that protein folding is more efficient when carried out by a chaperonin solution populated with a majority of symmetric GroEL(14)(GroES(7))(2) particles than by a majority of asymmetric GroEL(14)GroES(7) particles. The symmetric heterooligomer behaves as a highly efficient intermediate of the chaperonin protein folding cycle in vitro.