Setting the chaperonin timer: the effects of K+ and substrate protein on ATP hydrolysis.

The effects of potassium ion on the nested allostery of GroEL are due to increases in the affinity for nucleotide. Both positive allosteric transitions, TT-TR and TR-RR, occur at lower [ATP] as [K(+)] is increased. Negative cooperativity in the double-ringed system is also due to an increase in the affinity of the trans ring for the product ADP as [K(+)] is increased.