Abstract
Theoretical studies of protein folding suggest that multiple folding pathways should exist, but there is little experimental evidence to support this. Here we demonstrate changes in the flux between different transition states on parallel folding pathways, resulting in unprecedented upward curvature in the denaturant-dependent unfolding kinetics of a β-sandwich protein. As denaturant concentration increases, the highly compact transition state of one pathway becomes destabilized and the dominant flux of protein molecules shifts toward another pathway with a less structured transition state. Furthermore, point mutations alter the relative accessibility of the pathways, allowing the structure of two transition states on separate, direct folding pathways to be mapped by systematic Φ-value analysis. It has been suggested that pathways with diffuse rather than localized transition states are evolutionarily selected to prevent misfolding, and indeed we find that the transition state favored at high concentrations of denaturant is more polarized than the physiologically relevant one.
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13 July 2003
Replaced math image, appended PDF with correction info
Notes
*Note: In the version of this article initially published online, the parallel-pathway model appearing on page 2 contains a mistake. This mistake has been corrected for the HTML and print versions of the article.
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Acknowledgements
We thank C. Dobson for support and encouragement and S. Fowler and A. Fersht for helpful discussions. This work was supported by the Wellcome Trust (C.F.W., L.R. and J.C.). J.C. is a Wellcome Trust senior research fellow and C.F.W. holds a Wellcome Trust prize studentship.
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Wright, C., Lindorff-Larsen, K., Randles, L. et al. Parallel protein-unfolding pathways revealed and mapped. Nat Struct Mol Biol 10, 658–662 (2003). https://doi.org/10.1038/nsb947
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DOI: https://doi.org/10.1038/nsb947
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