Asymmetrical interaction of GroEL and GroES in the ATPase cycle of assisted protein folding |
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Authors: | MK Hayer-Hartl J Martin FU Hartl |
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Affiliation: | Howard Hughes Medical Institute, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA. |
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Abstract: | The chaperonins GroEL and GroES of Escherichia coli facilitate protein folding in an adenosine triphosphate (ATP)-dependent reaction cycle. The kinetic parameters for the formation and dissociation of GroEL-GroES complexes were analyzed by surface plasmon resonance. Association of GroES and subsequent ATP hydrolysis in the interacting GroEL toroid resulted in the formation of a stable GroEL:ADP:GroES complex. The complex dissociated as a result of ATP hydrolysis in the opposite GroEL toroid, without formation of a symmetrical GroEL:(GroES)2 intermediate. Dissociation was accelerated by the addition of unfolded polypeptide. Thus, the functional chaperonin unit is an asymmetrical GroEL:GroES complex, and substrate protein plays an active role in modulating the chaperonin reaction cycle. |
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