Limits of protein folding inside GroE complexes.

The GroE chaperones of Escherichia coli promote the folding of other proteins under conditions where no spontaneous folding occurs. One requirement for this reaction is the trapping of the nonnative protein inside the chaperone complex. Encapsulation may be important to prevent unfavorable intermolecular interactions during folding. We show here that, especially for oligomeric proteins, the timing of encapsulation and release is of critical importance. If this cycle is decelerated, misfolding is observed inside functional chaperone complexes.