Analysis of GroE-assisted folding under nonpermissive conditions. |
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Authors: | H Grallert J Buchner |
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Affiliation: | Institut für Organische Chemie and Biochemie, Technische Universit?t München, Lichtenbergstrasse 4, 85747 Garching, Germany. |
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Abstract: | 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. |
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