Conformational detours during folding of a collapsed state

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The protein S6 is a useful model to probe the role of partially folded states in the folding process. In the absence of salt, S6 folds from the denatured state D to the native state N without detectable intermediates. High concentrations of sodium sulfate induce the accumulation of a collapsed state C, which is off the direct folding route. However, the mutation VA85 enables S6 to fold from C directly to N through the transition state TSC. According to the denaturant dependence of this reaction, TSC and C are equally compact, but the data are difficult to deconvolute. Therefore, I have measured the heat capacities (ΔCp) for the D→C and C→TSC transitions. The ΔCp-values suggest that C needs to increase its surface area in order to fold directly to N. This underlines that it is a misfolded state that can only fold by at least partial unfolding. In contrast to the C-state formed by S6 wildtype, the VA85 C-state is just as compact as the native state, and this may be a prerequisite for direct folding. Individual "gatekeeper" residues may thus play a disproportionately large role in guiding proteins through different folding pathways.

Original languageEnglish
JournalBiochimica et Biophysica Acta - Proteins and Proteomics
Volume1750
Issue2
Pages (from-to)146-153
Number of pages8
ISSN1570-9639
DOIs
Publication statusPublished - 30 Jun 2005

    Research areas

  • Detour, Energy landscape, Heat capacity, Intermediate, Misfolded state, Protein folding

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