The reaction cycle of GroEL and GroES in chaperonin-assisted protein folding

Abstract

The reaction mechanism of protein folding by the chaperonin GroEL and its regulator GroES has been defined. GroES and substrate protein counteract each other's effects on GroEL: whereas GroES stabilizes GroEL in the ADP-bound state, binding of unfolded polypeptide within the cavity of the GroEL cylinder triggers ADP and GroES release. Upon ADP-ATP exchange, GroES reassociates with GroEL and ATP hydrolysis discharges the bound protein for folding. Partially folded protein rebinds to the chaperonin, thus perpetuating the cycle until folding is complete.