Preparation and characterization of Heparin induced GAPDH oligomers ables to interact with alpha-synuclein oligomers

DEFONSI E; VERA C; TORRES-BUGEAU C; BELLOMIO A; BARBOSA L; ITRI R; AVILA C; CHEHIN R

San Javier, Tucumán

Congreso; XLI Reunión Anual de la Sociedad Argentina de Biofísica. Simposio Satélite BIOTOX. Toxins of interest for Biomedicine; 2012

SAB - Sociedad Argentina de Biofísica

The aggregation of the protein α-synuclein contributes to neuronal toxicity in Parkinson´s disease. Oligomeric intermediates in the amyloid aggregation of α-synuclein have been found to be more toxic to cells than its monomeric or fibrillar forms. Heparin-induced GAPDH oligomeric species are able to alter the aggregation kinetic of α-synuclein promoting its conversion from oligomeric to fibrillar state. It was also demonstrated by our group that the presence of heparin-induced GAPDH oligomeric species decrease the toxic effects of α-synuclein oligomers in dopaminergic neurons. Oligomeric GAPDH species with ability to interact with α-synuclein were produced,purified and structurally characterized. These oligomeric species are metastable and exist in dynamically changing mixtures including tetramers, dimmers and oligomers of different sizes. The oligomeric species were stabilized through photocrosslinking, and further purified using molecularexclusion chromathography and identified by SDS-PAGE. Structural characterization of the species was performed using infrared spectroscopy and small angle X-Ray scattering. Herein, the first model from SAXS analysis of the early oligomeric structure of GAPDH amyloid-like speciesinduced by heparin binding is presented. Upon heparin binding, the tetrameric state of the GAPDH is lost and structurally modified dimmer species could be observed. Using these dimmer as building block, an experimentally-guided model was obtained from docking and moleculardynamics techniques.