A protein folding pathway with multiple folding intermediates at atomic resolution

AUTOR(ES)
FONTE

National Academy of Sciences

RESUMO

Using native-state hydrogen-exchange-directed protein engineering and multidimensional NMR, we determined the high-resolution structure (rms deviation, 1.1 Å) for an intermediate of the four-helix bundle protein: Rd-apocytochrome b562. The intermediate has the N-terminal helix and a part of the C-terminal helix unfolded. In earlier studies, we also solved the structures of two other folding intermediates for the same protein: one with the N-terminal helix alone unfolded and the other with a reorganized hydrophobic core. Together, these structures provide a description of a protein folding pathway with multiple intermediates at atomic resolution. The two general features for the intermediates are (i) native-like backbone topology and (ii) nonnative side-chain interactions. These results have implications for important issues in protein folding studies, including large-scale conformation search, φ-value analysis, and computer simulations.

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