The lower hydrolysis of ATP by the stress protein GroEL is a major factor responsible for the diminished chaperonin activity at low temperature

The chaperonins GroEL and GroES were shown to facilitate the refolding of u rea-unfolded rhodanese in an ATP-dependent process at 25 or 37 degreesC. A diminished chaperonin activity was observed at 10 degreesC, however, At low temperature. GroEL retains irs ability to Form a complex with urea-unfolde d rhodanese or with GroES. GroEL is also able to bind ATP at 10 degreesC. I nterestingly, the ATPase activity of GroEL was highly decreased at low temp eratures. Hydrolysis of ATP by GroEL was 60%; less at 10 degreesC than ar 2 5 degreesC. We conclude that the reduced hydrolysis of ATP by GroEL is a ma jor but perhaps not the only Factor responsible for the diminished chaperon in activity at 10 degreesC, GroEL may Function primarily at higher temperat ures in which the ability of GroEL to hydrolyze ATP is nor compromised. (C) 2000 Academic Press.