title: A single amino acid substitution differentiates Hsp70-dependent effects on alpha-synuclein degradation and toxicity.
abstract: alpha-Synuclein aggregation and toxicity play a major role in Parkinson's disease and dementia with Lewy bodies. Hsp70 is a multipurpose stress response chaperone protein that mediates both refolding and degradation of misfolded proteins. We have shown that Hsp70 is able to block both alpha-synuclein toxicity and aggregation. Here we introduce a mutation into the ATPase domain of Hsp70 (K71S) and demonstrate that this abolishes Hsp70 refolding activity. Nonetheless, Hsp70K71S continues to mediate alpha-synuclein degradation and blocks aggregate formation. In contrast to wild type Hsp70, the ATPase domain mutant mediates alpha-synuclein degradation through a non-proteasome inhibitor sensitive pathway. Although Hsp70K71S can diminish levels of alpha-synuclein to an even greater extent than Hsp70, HSP70K71S does not protect against alpha-synuclein toxicity. The Hsp70K71S mutant appears to dissociate the formation of aggregates, which it blocks, and toxicity, which it does not block. These data suggest that the ability of Hsp70 to prevent toxicity is distinct from degradation of alpha-synuclein and is dependent on its ATPase domain.
authors.affiliation: MassGeneral Institute for Neurodegenerative disease, Alzheimer Disease Research Unit, Massachusetts General Hospital, 114 16th Street, Charlestown, MA 02129, USA.
authors.forename: Jochen
authors.initials: J
authors.lastname: Klucken
authors.forename: Youngah
authors.initials: Y
authors.lastname: Shin
authors.forename: Bradley T
authors.initials: BT
authors.lastname: Hyman
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: McLean
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D045744:Cell Line, Tumor; D004331:Drosophila melanogaster; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D020961:Lewy Body Disease / Q000378:metabolism; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism* / Q000633:toxicity*; D010300:Parkinson Disease / Q000378:metabolism; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D051843:Synucleins; D051844:alpha-Synuclein
chemical_list: D018840:HSP70 Heat-Shock Proteins; D009419:Nerve Tissue Proteins; C497604:SNCA protein, human; D051843:Synucleins; D051844:alpha-Synuclein