title: Tuning the free-energy landscape of a WW domain by temperature, mutation, and truncation.
abstract: The equilibrium unfolding of the Formin binding protein 28 (FBP) WW domain, a stable three-stranded beta-sheet protein, can be described as reversible apparent two-state folding. Kinetics studied by laser temperature jump reveal a third state at temperatures below the midpoint of unfolding. The FBP free-energy surface can be tuned between three-state and two-state kinetics by changing the temperature, by truncation of the C terminus, or by selected point mutations. FBP WW domain is the smallest three-state folder studied to date and the only one that can be freely tuned between three-state and apparent two-state folding by several methods (temperature, truncation, and mutation). Its small size (28-37 residues), the availability of a quantitative reaction coordinate (phi(T)), the fast folding time scale (10s of micros), and the tunability of the folding routes by small temperature or sequence changes make this system the ideal prototype for studying more subtle features of the folding free-energy landscape by simulations or analytical theory.
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Houbi
authors.initials: H
authors.lastname: Nguyen
authors.forename: Marcus
authors.initials: M
authors.lastname: Jager
authors.forename: Alessandro
authors.initials: A
authors.lastname: Moretto
authors.forename: Martin
authors.initials: M
authors.lastname: Gruebele
authors.forename: Jeffery W
authors.initials: JW
authors.lastname: Kelly
mesh_terms: D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics*; D003001:Cloning, Molecular; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016133:Polymerase Chain Reaction; D011487:Protein Conformation; D011489:Protein Denaturation; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D017384:Sequence Deletion; D013816:Thermodynamics
chemical_list: D002352:Carrier Proteins; D011994:Recombinant Proteins; C473939:formin binding protein 28, human