title: Transient sampling of aggregation-prone conformations causes pathogenic instability of a parkinsonian mutant of DJ-1 at physiological temperature.
abstract: Various missense mutations in the cytoprotective protein DJ-1 cause rare forms of inherited parkinsonism. One mutation, M26I, diminishes DJ-1 protein levels in the cell but does not result in large changes in the three-dimensional structure or thermal stability of the protein. Therefore, the molecular defect that results in loss of M26I DJ-1 protective function is unclear. Using NMR spectroscopy near physiological temperature, we found that the picosecond-nanosecond dynamics of wild-type and M26I DJ-1 are similar. In contrast, elevated amide hydrogen/deuterium exchange rates indicate that M26I DJ-1 is more flexible than the wild-type protein on longer timescales and that hydrophobic regions of M26I DJ-1 are transiently exposed to solvent. Tryptophan fluorescence spectroscopy and thiol crosslinking analyzed by mass spectrometry also demonstrate that M26I DJ-1 samples conformations that differ from the wild-type protein at 37°C. These transiently sampled conformations are unstable and cause M26I DJ-1 to aggregate in vitro at physiological temperature but not at lower temperatures. M26I DJ-1 aggregation is correlated with pathogenicity, as the structurally similar but non-pathogenic M26L mutation does not aggregate at 37°C. The onset of dynamically driven M26I DJ-1 instability at physiological temperature resolves conflicting literature reports about the behavior of this disease-associated mutant and illustrates the pitfalls of characterizing proteins exclusively at room temperature or below, as key aspects of their behavior may not be apparent.
authors.affiliation: Department of Biochemistry and the Redox Biology Center, University of Nebraska-Lincoln, Lincoln, Nebraska, 68588.
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Milkovic
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, 68588.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Catazaro
authors.affiliation: Department of Biochemistry and the Redox Biology Center, University of Nebraska-Lincoln, Lincoln, Nebraska, 68588.
authors.forename: Jiusheng
authors.initials: J
authors.lastname: Lin
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, 68588.
authors.forename: Steven
authors.initials: S
authors.lastname: Halouska
authors.affiliation: Department of Biochemistry and the Redox Biology Center, University of Nebraska-Lincoln, Lincoln, Nebraska, 68588.|Department of Biochemistry, Spring Hill College, Mobile, Alabama, 36608.
authors.forename: James L
authors.initials: JL
authors.lastname: Kizziah
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, 68588.
authors.forename: Sara
authors.initials: S
authors.lastname: Basiaga
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, 68588.
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Cerny
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, 68588.
authors.forename: Robert
authors.initials: R
authors.lastname: Powers
authors.affiliation: Department of Biochemistry and the Redox Biology Center, University of Nebraska-Lincoln, Lincoln, Nebraska, 68588.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Wilson
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D009154:Mutation / Q000235:genetics; D010300:Parkinson Disease / Q000235:genetics*; D000071617:Protein Deglycase DJ-1 / Q000737:chemistry* / Q000235:genetics*; D013696:Temperature
chemical_list: C105131:PARK7 protein, human; D000071617:Protein Deglycase DJ-1
keywords: DJ-1; PARK7; Parkinson's disease; conformational dynamics; protein stability; thiol crosslinking