Influence of the GroE molecular chaperone machine on the in vitro refolding of Escherichia coli β‐galactosidase

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Abstract
We have studied the effect of the components of the GroE molecular chaperone machine on the refolding of the Escherichia coli enzyme β‐galactosidase, a tetrameric protein whose 116‐kDa protomers should not completely fit within the central cavity of the GroEL toroid. In the absence of other additives, GroEL formed a weak complex with chemically denatured β‐galactosidase, reduced its propensity to aggregate, and increased the recovery yields of active enzyme twofold without altering its folding pathway. When present together with the chaperonin, ATP —and to a lesser extent AMP‐PNP —reduced the recovery yields and led to the resumption of aggregation. The use of the complete chaperonin system (GroEL, GroES, and ATP) eliminated the GroEL‐mediated increase in recovery and folding proceeded less efficiently than in buffer alone. This unusual behavior can be explained in terms of a chaperonin “buffering” effect and the different affinities of GroE complexes for denatured β‐galactosidase.
Funding Information
  • NSF award (BES-9501212)