title: The mechanism of denaturation and the unfolded state of the α-helical membrane-associated protein Mistic.
abstract: In vitro protein-folding studies using chemical denaturants such as urea are indispensible in elucidating the forces and mechanisms determining the stability, structure, and dynamics of water-soluble proteins. By contrast, α-helical membrane-associated proteins largely evade such approaches because they are resilient to extensive unfolding. We have used optical and NMR spectroscopy to provide an atomistic-level dissection of the effects of urea on the structure and dynamics of the α-helical membrane-associated protein Mistic as well as its interactions with detergent and solvent molecules. In the presence of the zwitterionic detergent lauryl dimethylamine oxide, increasing concentrations of urea result in a complex sequence of conformational changes that go beyond simple two-state unfolding. Exploiting this finding, we report the first high-resolution structural models of the urea denaturation process of an α-helical membrane-associated protein and its completely unfolded state, which contains almost no regular secondary structure but nevertheless retains a topology close to that of the folded state.
authors.affiliation: Center for Integrated Protein Science Munich, Department Chemie, Technische Universität München , Lichtenbergstraße 4, 85747 Garching, Germany.
authors.forename: Tomas
authors.initials: T
authors.lastname: Jacso
authors.forename: Benjamin
authors.initials: B
authors.lastname: Bardiaux
authors.forename: Jana
authors.initials: J
authors.lastname: Broecker
authors.forename: Sebastian
authors.initials: S
authors.lastname: Fiedler
authors.forename: Tom
authors.initials: T
authors.lastname: Baerwinkel
authors.forename: Andi
authors.initials: A
authors.lastname: Mainz
authors.forename: Uwe
authors.initials: U
authors.lastname: Fink
authors.forename: Carolyn
authors.initials: C
authors.lastname: Vargas
authors.forename: Hartmut
authors.initials: H
authors.lastname: Oschkinat
authors.forename: Sandro
authors.initials: S
authors.lastname: Keller
authors.forename: Bernd
authors.initials: B
authors.lastname: Reif
mesh_terms: D000595:Amino Acid Sequence; D008565:Membrane Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011489:Protein Denaturation; D017386:Sequence Homology, Amino Acid; D012995:Solubility
chemical_list: D008565:Membrane Proteins