title: A protein folding pathway with multiple folding intermediates at atomic resolution.
abstract: Using native-state hydrogen-exchange-directed protein engineering and multidimensional NMR, we determined the high-resolution structure (rms deviation, 1.1 angstroms) 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, -value analysis, and computer simulations.
authors.affiliation: Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Building 37, Room 6114E, Bethesda, MD 20892, USA.
authors.forename: Hanqiao
authors.initials: H
authors.lastname: Feng
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhou
authors.forename: Yawen
authors.initials: Y
authors.lastname: Bai
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D015786:Cytochromes b5 / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry; D008958:Models, Molecular; D009584:Nitrogen / Q000737:chemistry; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular; D015202:Protein Engineering; D017510:Protein Folding; D017434:Protein Structure, Tertiary
chemical_list: D009587:Nitrogen Isotopes; D006859:Hydrogen; D015786:Cytochromes b5; D009584:Nitrogen