title: Pathogenic mutations shift the equilibria of alpha-synuclein single molecules towards structured conformers.
abstract: Alpha-synuclein (alpha-Syn) is an abundant brain protein whose mutations have been linked to early-onset Parkinson's disease (PD). We recently demonstrated, by means of a single-molecule force spectroscopy (SMFS) methodology, that the conformational equilibrium of monomeric wild-type (WT) alpha-Syn shifts toward beta-containing structures in several unrelated conditions linked to PD pathogenicity. Herein, we follow the same methodology previously employed for WT alpha-Syn to characterize the conformational heterogeneity of pathological alpha-Syn mutants A30P, A53T, and E46K. Contrary to the bulk ensemble-averaged spectroscopies so far employed to this end by different authors, our single-molecule methodology monitored marked differences in the conformational behaviors of the mutants with respect to the WT sequence. We found that all the mutants have a much higher propensity than the WT to adopt a monomeric compact conformation that is compatible with the acquiring of beta structure. Mutants A30P and A53T show a similar conformational equilibrium that is significantly different from that of E46K. Another class of conformations, stabilized by mechanically weak interactions (MWI), shows a higher variety in the mutants than in the WT protein. In the A30P mutant these interactions are relatively stronger, and therefore the corresponding conformations are possibly more structured. The more structured and globular conformations of the mutants can explain their higher propensity to aggregate with respect to the WT.
authors.affiliation: Department of Biochemistry, University of Bologna, via Irnerio 48, Bologna, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Brucale
authors.forename: Massimo
authors.initials: M
authors.lastname: Sandal
authors.forename: Selena
authors.initials: S
authors.lastname: Di Maio
authors.forename: Aldo
authors.initials: A
authors.lastname: Rampioni
authors.forename: Isabella
authors.initials: I
authors.lastname: Tessari
authors.forename: Laura
authors.initials: L
authors.lastname: Tosatto
authors.forename: Marco
authors.initials: M
authors.lastname: Bisaglia
authors.forename: Luigi
authors.initials: L
authors.lastname: Bubacco
authors.forename: Bruno
authors.initials: B
authors.lastname: Samorì
mesh_terms: D001696:Biomechanical Phenomena; D004926:Escherichia coli / Q000235:genetics; D050506:Mutant Chimeric Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D050505:Mutant Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D011487:Protein Conformation; D011489:Protein Denaturation; D013057:Spectrum Analysis; D051844:alpha-Synuclein / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism
chemical_list: D050506:Mutant Chimeric Proteins; D050505:Mutant Proteins; D051844:alpha-Synuclein