Role of different regions of alpha-synuclein in the assembly of fibrils.
Elucidating the details of the assembly of amyloid fibrils is a key step to understanding the mechanism of amyloid deposition diseases including Parkinson's disease. Although several models have been proposed, based on analyses of polypeptides and short peptides, a detailed understanding of the structure and mechanism of alpha-synuclein fibrillation remains elusive. In this study, we used trypsin and endoproteinase GluC to digest intact alpha-synuclein fibrils and to analyze the detailed morphology of the resultant fibrils/remnants. We also created three mutants of alpha-synuclein, in which the N-terminal and C-terminal regions were removed, both individually and in combination, and investigated the detailed morphology of the fibrils from these mutants. Our results indicate that the assembly of mature alpha-synuclein fibrils is hierarchical: protofilaments --> protofibrils --> mature fibrils. There is a core region of approximately 70 amino acids, from residues approximately 32 to 102, which comprises the beta-rich core of the protofilaments and fibrils. In contrast, the two terminal regions show no evidence of participating in the assembly of the protofilament core but play a key role in the interactions between the protofilaments, which is necessary for the fibril maturation.
Qin
Zhijie
Z
Department of Chemistry & Biochemistry, University of California, Santa Cruz, California 95064, USA.
Hu
Dongmei
D
Han
Shubo
S
Hong
Dong-Pyo
DP
Fink
Anthony L
AL
D000595:Amino Acid Sequence; D000682:Amyloid / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D003461:Crystallography; D006801:Humans; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D012697:Serine Endopeptidases / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism; D051844:alpha-Synuclein / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure
D000682:Amyloid; C497604:SNCA protein, human; D051844:alpha-Synuclein; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase; D014357:Trypsin