Journal Article

New SNCA mutation and structures of α-synuclein filaments from juvenile-onset synucleinopathy

Bacioglu, Mehtap, Ghetti, Bernardino, Garringer, Holly J., Vidal, Ruben, Lövestam, Sofia, Yang, Yang, Spillantini, Maria Grazia, Takao, Masaki, Shi, Yang, Koto, Atsuo, Murzin, Alexey G., Peak-Chew, Sew, Scheres, Sjors H. W., Kotecha, Abhay, Zhang, Xianjun, Goedert, Michel

2023

Overview

A 21-nucleotide duplication in one allele of SNCA was identified in a previously described disease with abundant α-synuclein inclusions that we now call juvenile-onset synucleinopathy (JOS). This mutation translates into the insertion of MAAAEKT after residue 22 of α-synuclein, resulting in a protein of 147 amino acids. Both wild-type and mutant proteins were present in sarkosyl-insoluble material that was extracted from frontal cortex of the individual with JOS and examined by electron cryo-microscopy. The structures of JOS filaments, comprising either a single protofilament, or a pair of protofilaments, revealed a new α-synuclein fold that differs from the folds of Lewy body diseases and multiple system atrophy (MSA). The JOS fold consists of a compact core, the sequence of which (residues 36–100 of wild-type α-synuclein) is unaffected by the mutation, and two disconnected density islands (A and B) of mixed sequences. There is a non-proteinaceous cofactor bound between the core and island A. The JOS fold resembles the common substructure of MSA Type I and Type II dimeric filaments, with its core segment approximating the C-terminal body of MSA protofilaments B and its islands mimicking the N-terminal arm of MSA protofilaments A. The partial similarity of JOS and MSA folds extends to the locations of their cofactor-binding sites. In vitro assembly of recombinant wild-type α-synuclein, its insertion mutant and their mixture yielded structures that were distinct from those of JOS filaments. Our findings provide insight into a possible mechanism of JOS fibrillation in which mutant α-synuclein of 147 amino acids forms a nucleus with the JOS fold, around which wild-type and mutant proteins assemble during elongation.

• Publisher: Springer Berlin Heidelberg,Springer Nature B.V
• Subject: alpha-Synuclein - genetics / alpha-Synuclein - metabolism / Amino acids / Atrophy / Cortex (frontal) / Filaments / Humans / Islands / Lewy bodies / Medicine / Medicine & Public Health / Multiple System Atrophy - genetics / Multiple System Atrophy - metabolism / Mutants / Mutation / Mutation - genetics / Neurosciences / Nigeria / Original Paper / Parkinson's disease / Pathology / Synuclein / Synucleinopathies - genetics