conformational equilibria in monomeric α-synuclein at the single-molecule level在单体的构象平衡α-synuclein在单分子水平.pdfVIP

PLoS BIOLOGY Conformational Equilibria in Monomeric a-Synuclein at the Single-Molecule Level 1[ 1,2[* 3 4 3 Massimo Sandal , Francesco Valle , Isabella Tessari , Stefano Mammi , Elisabetta Bergantino , Francesco Musiani1 1 3 `1,2* , Marco Brucale , Luigi Bubacco , Bruno Samorı 1 Department of Biochemistry ‘‘G. Moruzzi’’, University of Bologna, Bologna, Italy, 2 National Center on Nanostructures and BioSystems at Surfaces (S3) INFM-CNR, Modena, Italy, 3 Department of Biology, University of Padova, Padova, Italy, 4 Department of Chemical Sciences, University of Padova, Padova, Italy Human a-Synuclein (aSyn) is a natively unfolded protein whose aggregation into amyloid fibrils is involved in the pathology of Parkinson disease. A full comprehension of the structure and dynamics of early intermediates leading to the aggregated states is an unsolved problem of essential importance to researchers attempting to decipher the molecular mechanisms of aSyn aggregation and formation of fibrils. Traditional bulk techniques used so far to solve this problem point to a direct correlation between aSyn’s unique conformational properties and its propensity to aggregate, but these techniques can only provide ensemble-averaged information for monomers and oligomers alike. They therefore cannot characterize the full complexity of the conformational equilibria that trigger the aggregation process. We applied atomic force microscopy–based single-molecule mechanical unfolding methodology to study the conformational equilibrium of human wild-type and mutant aSyn. The conformational heterogeneity of monomeric aSyn was characterized at the single-molecule level. Three main classes of conformations, inclu