Analysis of GroE-assisted folding under nonpermissive conditions.
The molecular chaperones GroEL and GroES facilitate protein folding in an ATP-dependent manner under conditions where no spontaneous folding occurs. It has remained unknown whether GroE achieves this by a passive sequestration of protein inside the GroE cavity or by changing the folding pathway of a protein. Here we used citrate synthase, a well studied model substrate, to discriminate between these possibilities. We demonstrate that GroE maintains unfolding intermediates in a state that allows productive folding under nonpermissive conditions. During encapsulation of non-native protein inside GroEL.GroES complexes, a folding reaction takes place, generating association-competent monomeric intermediates that are no longer recognized by GroEL. Thus, GroE shifts folding intermediates to a productive folding pathway under heat shock conditions where even the native protein unfolds in the absence of GroE.
Institut für Organische Chemie and Biochemie, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
H
H
Grallert
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J
Buchner
D018835:Chaperonin 10 / Q000378:metabolism*; D018834:Chaperonin 60 / Q000378:metabolism*; D002950:Citrate (si)-Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D006358:Hot Temperature; D007700:Kinetics; D011489:Protein Denaturation; D017510:Protein Folding; D011994:Recombinant Proteins / Q000378:metabolism
D018835:Chaperonin 10; D018834:Chaperonin 60; D011994:Recombinant Proteins; D002950:Citrate (si)-Synthase