THE ATPASE ACTIVITY OF CHAPERONIN GROEL IS HIGHLY STIMULATED AT ELEVATED-TEMPERATURES

The chaperonin GroEL is a heat-shock protein that stabilizes folding i ntermediates by forming binary complexes. The release of bound polypep tides as active proteins requires ATP hydrolysis by GroEL. The ability of GroEL to support the folding of urea-unfolded rhodanese and to hyd rolyze ATP was investigated at high temperatures. We found that the ch aperonin-mediated folding of rhodanese and the ATPase activity of GroE L are temperature dependent. The GroEL ATPase activity, however, incre ases very strongly over the range of temperatures that is physiologica lly relevant for Escherichia coli growth. Further, GroES partially sup presses the GroEL ATPase activity in the same temperature range. (C) 1 996 Academic Press, Inc.