title: Parallel protein-unfolding pathways revealed and mapped.
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 beta-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 Phi-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.
authors.affiliation: Department of Chemistry, University of Cambridge, MRC Centre for Protein Engineering, Lensfield Road, Cambridge CB2 1EW, UK.
authors.forename: Caroline F
authors.initials: CF
authors.lastname: Wright
authors.forename: Kresten
authors.initials: K
authors.lastname: Lindorff-Larsen
authors.forename: Lucy G
authors.initials: LG
authors.lastname: Randles
authors.forename: Jane
authors.initials: J
authors.lastname: Clarke
mesh_terms: D064211:Connectin; D003598:Cytoskeletal Proteins; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008840:Microfilament Proteins; D008958:Models, Molecular; D009124:Muscle Proteins / Q000737:chemistry / Q000235:genetics; D017354:Point Mutation; D011489:Protein Denaturation; D017510:Protein Folding; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics
chemical_list: D064211:Connectin; D003598:Cytoskeletal Proteins; C577290:MYOT protein, human; D008840:Microfilament Proteins; D009124:Muscle Proteins; D011506:Proteins; D011994:Recombinant Proteins; C577285:TTN protein, human; D011494:Protein Kinases