Diverse metastable structures formed by small oligomers of α-synuclein probed by force spectroscopy.
Oligomeric aggregates are widely suspected as toxic agents in diseases caused by protein aggregation, yet they remain poorly characterized, partly because they are challenging to isolate from a heterogeneous mixture of species. We developed an assay for characterizing structure, stability, and kinetics of individual oligomers at high resolution and sensitivity using single-molecule force spectroscopy, and applied it to observe the formation of transient structured aggregates within single oligomers of α-synuclein, an intrinsically-disordered protein linked to Parkinson's disease. Measurements of the molecular extension as the proteins unfolded under tension in optical tweezers revealed that even small oligomers could form numerous metastable structures, with a surprisingly broad range of sizes. Comparing the structures formed in monomers, dimers and tetramers, we found that the average mechanical stability increased with oligomer size. Most structures formed within a minute, with size-dependent rates. These results provide a new window onto the complex α-synuclein aggregation landscape, characterizing the microscopic structural heterogeneity and kinetics of different pathways.
Department of Physics, University of Alberta, Edmonton, Alberta, Canada.
Krishna
K
Neupane
Department of Physics, University of Alberta, Edmonton, Alberta, Canada.
Allison
A
Solanki
National Institute for Nanotechnology, National Research Council Canada, Edmonton, Alberta, Canada.
Iveta
I
Sosova
National Institute for Nanotechnology, National Research Council Canada, Edmonton, Alberta, Canada.
Miro
M
Belov
Department of Physics, University of Alberta, Edmonton, Alberta, Canada ; National Institute for Nanotechnology, National Research Council Canada, Edmonton, Alberta, Canada.
Michael T
MT
Woodside
D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D007700:Kinetics; D052898:Optical Tweezers; D066329:Protein Aggregates; D015202:Protein Engineering; D020836:Protein Structure, Quaternary; D058767:Protein Unfolding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D013057:Spectrum Analysis / Q000379:methods; D013816:Thermodynamics; D051844:alpha-Synuclein / Q000737:chemistry* / Q000235:genetics
D066329:Protein Aggregates; D011994:Recombinant Proteins; D051844:alpha-Synuclein