title: Mechanism of cleavage of alpha-synuclein by the 20S proteasome and modulation of its degradation by the RedOx state of the N-terminal methionines.
abstract: Alpha-synuclein is a small protein implicated in the pathophysiology of Parkinson's disease (PD). We have investigated the mechanism of cleavage of alpha-synuclein by the 20S proteasome. Alpha-synuclein interacts with the C8 (α7) subunit of the proteasome. The N-terminal part of alpha-synuclein (amino acids 1-60) is essential for its proteasomal degradation and analysis of peptides released from proteasomal digestion allows concluding that initial cleavages occur within the N-terminal region of the molecule. Aggregated alpha-synucleins are also degraded by the proteasome with a reduced rate, likely due to Met oxidation. In fact, mild oxidation of alpha-synuclein with H2O2 resulted in the inhibition of its degradation by the proteasome, mainly due to oxidation of Met 1 and 5 of alpha-synuclein. The inhibition was reversed by treatment of the oxidized protein with methionine sulfoxide reductases (MsrA plus MsrB). Similarly, treatment with H2O2 of N2A cells transfected with alpha-synuclein resulted in the inhibition of its degradation that was also reverted by co-transfection of MsrA plus MsrB. These results clearly indicate that oxidative stress, a common feature of PD and other synucleinopathies, promotes a RedOx change in the proteostasis of alpha-synuclein due to Met oxidation and reduced proteasomal degradation; compromised reversion of those oxidative changes would result in the accumulation of oxidative damaged alpha-synuclein likely contributing to the pathogenesis of PD.
authors: Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols", UAM-CSIC y Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain.
authors: Beatriz
authors: B
authors: Alvarez-Castelao
authors: Department of Biochemistry, Ghent University, Ghent, Belgium; Department of Medical Protein Research, VIB, Ghent Univeristy, Ghent, Belgium.
authors: Marc
authors: M
authors: Goethals
authors: Department of Biochemistry, Ghent University, Ghent, Belgium; Department of Medical Protein Research, VIB, Ghent Univeristy, Ghent, Belgium.
authors: Joël
authors: J
authors: Vandekerckhove
authors: Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols", UAM-CSIC y Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Spain; Department of Biochemistry, Ghent University, Ghent, Belgium. Electronic address: joseg.castano@uam.es.
authors: José G
authors: JG
authors: Castaño
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015151:Immunoblotting; D008715:Methionine / Q000378:metabolism*; D051150:Methionine Sulfoxide Reductases / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D025941:Protein Interaction Mapping; D020836:Protein Structure, Quaternary; D021122:Protein Subunits / Q000378:metabolism; D059748:Proteolysis / Q000187:drug effects; D051381:Rats; D016622:Silver Staining; D051844:alpha-Synuclein / Q000737:chemistry / Q000378:metabolism*
chemical_list: D010455:Peptides; D021122:Protein Subunits; D051844:alpha-Synuclein; D008715:Methionine; D006861:Hydrogen Peroxide; D051150:Methionine Sulfoxide Reductases; D046988:Proteasome Endopeptidase Complex
keywords: Alpha-synuclein; MsrA and B; Parkinson's disease; Proteasome; Protein degradation; RedOx