Rapid self-assembly of α-synuclein observed by in situ atomic force microscopy

摘要: Self-assembly of α-synuclein resulting in protein aggregates diverse morphology has been implicated the pathogenesis Parkinson's disease and other neurodegenerative disorders known as synucleinopathies. Apart from its biomedical relevance, this aggregation process is representative interconversion an unfolded into nanostructures with typical amyloid features. We have used situ tapping mode atomic force microscopy to continuously monitor self-assembly wild-type α-synuclein, disease-related mutants A30P A53T, C-terminally truncated variant α-synuclein(1–108). Different modes were observed depending on experimental conditions, i.e. pH, concentration, polyamine temperature supporting substrate. At pH 7.5, absence biogenic polyamines spermidine or spermine, elongated sheets 1.1(±0.2) nm height presumably representing individual β-sheet structures, formed mica substrates within a few minutes. Their orientation was directed by crystalline substructure In contrast, sheet formation not hydrophobic highly oriented pyrolytic graphite substrates, suggesting that negatively charged surfaces promote self-assembly. presence spermine 5.9(±1.0) high spheroidal structures preferentially formed, sharing characteristics similar previously reported for several amyloidogenic proteins linked neurotoxicity. α-Synuclein spheroid depended critically binding C terminus, revealing promoting effect terminus assembly bound state. rare cases, fibril growth spheroids preformed observed. 5.0, fibrils initially incorporated amorphous course process, providing evidence potential act nucleation sites aggregation. This study provides direct insight different identifies key factors modulating process.