Mapping the transition state of the allosteric pathway of GroEL by protein engineering

A nested model for cooperativity in adenosine triphosphate (ATP) hydrolysis by the chaperonin GroEL, an allosteric protein, was described. GroEL facilitates protein folding in vivo and in vitro in an ATP-regulated manner and consists of 14 similar subunits that form two stacked heptameric rings with a central cavity. The model shows each ring to be in equilibrium between a tense state, with high affinity for nonfolded proteins and low affinity for ATP, and a relaxed state, with low affinity for nonfolded proteins and high affinity for ATP.