Role of alpha-synuclein carboxy-terminus on fibril formation in vitro

Biochemistry. 2003 Jul 22;42(28):8530-40. doi: 10.1021/bi027363r.


Alpha-synuclein (alpha-syn) is the major component of intracellular inclusions in several neurodegenerative diseases, and the conversion of soluble alpha-syn into filamentous aggregates may contribute to disease pathogenesis. Since mechanisms leading to the formation of alpha-syn inclusions are unclear, in vitro models of alpha-syn aggregation may yield insights into this process. To that end, we examined the consequences on the progressive deletion of the carboxy-terminus of alpha-syn in regulating fibril formation, and we show here that carboxy-terminal truncated alpha-syn proteins aggregate faster than the full-length molecule. Protease digestion and immunoelectron microscopy indicate that the alpha-syn amino- and carboxy-termini are more solvent exposed than the central core and that filaments formed from carboxy-terminal truncated alpha-syn are narrower in diameter than the full-length molecule. Moreover, seeding experiments under conditions where full-length alpha-syn did not readily aggregate revealed that carboxy-truncated alpha-syn extending from amino acids 1-102 and 1-110 but not 1-120 were efficient in seeding full-length alpha-syn aggregation over a range of concentrations. Using site-directed mutagenesis, the negatively charged residues 104, 105 and 114, 115 in the carboxy-terminus were implicated in this reduced aggregation and the lack of seeding of full-length alpha-syn fibrillogenesis by 1-120. Our data support the view that the middle region of alpha-syn forms the core of alpha-syn filaments and that negative charges in the carboxy-terminus counteract alpha-syn aggregation. Thus, the carboxy-terminus of alpha-syn may regulate aggregation of full-length alpha-syn and determine the diameter of alpha-syn filaments.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Actin Cytoskeleton / ultrastructure*
  • Base Sequence
  • Cloning, Molecular
  • DNA Primers
  • Escherichia coli / enzymology
  • Escherichia coli / genetics
  • Humans
  • Microfibrils / ultrastructure*
  • Microscopy, Immunoelectron
  • Nerve Tissue Proteins / chemistry*
  • Nerve Tissue Proteins / isolation & purification
  • Nerve Tissue Proteins / metabolism*
  • Nerve Tissue Proteins / ultrastructure
  • Peptide Fragments / chemistry
  • Peptide Fragments / isolation & purification
  • Peptide Fragments / metabolism
  • Protein Structure, Secondary
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Recombinant Proteins / ultrastructure
  • Spectrometry, Fluorescence
  • Synucleins
  • alpha-Synuclein


  • DNA Primers
  • Nerve Tissue Proteins
  • Peptide Fragments
  • Recombinant Proteins
  • SNCA protein, human
  • Synucleins
  • alpha-Synuclein