title: Magnesium inhibits spontaneous and iron-induced aggregation of alpha-synuclein.
abstract: Multiple studies implicate metals in the pathophysiology of neurodegenerative diseases. Disturbances in brain iron metabolism are linked with synucleinopathies. For example, in Parkinson's disease, iron levels are increased and magnesium levels are reduced in the brains of patients. To understand how changes in iron and magnesium might affect the pathophysiology of Parkinson's disease, we investigated binding of iron to alpha-synuclein, which accumulates in Lewy bodies. Using fluorescence of the four tyrosines in alpha-synuclein as indicators of metal-related conformational changes in alpha-synuclein, we show that iron and magnesium both interact with alpha-synuclein. alpha-Synuclein exhibits fluorescence peaks at 310 and 375 nm. Iron lowers both fluorescence peaks, while magnesium increases the fluorescence peak only at 375 nm, which suggests that magnesium affects the conformation of alpha-synuclein differently than iron. Consistent with this hypothesis, we also observe that magnesium inhibits alpha-synuclein aggregation, measured by immunoblot, cellulose acetate filtration, or thioflavine-T fluorescence. In each of these studies, iron increases alpha-synuclein aggregation, while magnesium at concentrations >0.75 mm inhibits the aggregation of alpha-synuclein induced either spontaneously or by incubation with iron. These data suggest that the conformation of alpha-synuclein can be modulated by metals, with iron promoting aggregation and magnesium inhibiting aggregation.
authors.affiliation: Department of Pharmacology, Loyola University Medical Center, Maywood, Illinois 60153, USA.
authors.forename: Natalie
authors.initials: N
authors.lastname: Golts
authors.forename: Heather
authors.initials: H
authors.lastname: Snyder
authors.forename: Mark
authors.initials: M
authors.lastname: Frasier
authors.forename: Catherine
authors.initials: C
authors.lastname: Theisler
authors.forename: Peter
authors.initials: P
authors.lastname: Choi
authors.forename: Benjamin
authors.initials: B
authors.lastname: Wolozin
mesh_terms: D019943:Amino Acid Substitution; D002122:Calcium Chloride / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D006801:Humans; D007501:Iron / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000187:drug effects; D010750:Phosphoproteins / Q000737:chemistry / Q000187:drug effects; D011994:Recombinant Proteins / Q000737:chemistry / Q000187:drug effects; D013053:Spectrophotometry; D051843:Synucleins; D017967:Zinc Compounds / Q000494:pharmacology; D051844:alpha-Synuclein
chemical_list: D002712:Chlorides; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D011994:Recombinant Proteins; C497604:SNCA protein, human; D051843:Synucleins; D017967:Zinc Compounds; D051844:alpha-Synuclein; C016837:zinc chloride; D007501:Iron; D008274:Magnesium; D002122:Calcium Chloride