title: Structural Characterization of the Early Events in the Nucleation-Condensation Mechanism in a Protein Folding Process.
abstract: The nucleation-condensation mechanism represents a major paradigm to understand the folding process of many small globular proteins. Although substantial evidence has been acquired for this mechanism, it has remained very challenging to characterize the initial events leading to the formation of a folding nucleus. To achieve this goal, we used a combination of relaxation dispersion NMR spectroscopy and molecular dynamics simulations to determine ensembles of conformations corresponding to the denatured, transition, and native states in the folding of the activation domain of human procarboxypeptidase A2 (ADA2h). We found that the residues making up the folding nucleus tend to interact in the denatured state in a transient manner and not simultaneously, thereby forming incomplete and distorted versions of the folding nucleus. Only when all the contacts between these key residues are eventually formed can the protein reach the transition state and continue folding. Overall, our results elucidate the mechanism of formation of the folding nucleus of a protein and provide insights into how its folding rate can be modified during evolution by mutations that modulate the strength of the interactions between the residues forming the folding nucleus.
authors.affiliation: Department of Chemistry, University of Cambridge , Cambridge CB2 1EW, U.K.
authors.forename: Predrag
authors.initials: P
authors.lastname: Kukic
authors.affiliation: Department of Molecular Biology and Biophysics, University of Connecticut Health Center , Farmington, Connecticut 06030, United States.
authors.forename: Yulia
authors.initials: Y
authors.lastname: Pustovalova
authors.affiliation: Department of Chemistry, University of Cambridge , Cambridge CB2 1EW, U.K.|Technische Universität Mun̈chen Institute for Advanced Study & Department of Chemistry , Lichtenbergstr. 4, 85748 Garching, Germany.
authors.forename: Carlo
authors.identifier: 0000-0002-9923-8590
authors.initials: C
authors.lastname: Camilloni
authors.affiliation: Istituto Pasteur - Fondazione Cenci Bolognetti and Istituto di Biologia e Patologia Molecolari del CNR, Dipartimento di Scienze Biochimiche "A. Rossi Fanelli", Sapienza Università di Roma , Rome 00185, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Gianni
authors.affiliation: Department of Molecular Biology and Biophysics, University of Connecticut Health Center , Farmington, Connecticut 06030, United States.
authors.forename: Dmitry M
authors.initials: DM
authors.lastname: Korzhnev
authors.affiliation: Department of Chemistry, University of Cambridge , Cambridge CB2 1EW, U.K.
authors.forename: Michele
authors.identifier: 0000-0002-3616-1610
authors.initials: M
authors.lastname: Vendruscolo
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000378:metabolism; D004268:DNA-Binding Proteins; D006801:Humans; D056004:Molecular Dynamics Simulation; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D017510:Protein Folding; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; C097695:TADA2A protein, human; D014157:Transcription Factors