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

DEFONSI, E; VERA, C; TORRES-BUGEAU, CLARISA M; BELLOMIO, AUGUSTO; BARBOSA, LEANDRO R S; ITRI, ROSANGELA; AVILA CL; CHEHIN, RN

San Javier

Congreso; XLI Reunion Anual de la Sociedad Argentina de Biofisica; 2012

Sociedad Argentina de Biofisica

The aggregation of the protein alfa-synuclein (AS) contributes to neuronal toxicity in Parkinson´s disease. Oligomeric intermediates in the amyloid aggregation of AS 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 AS 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 AS oligomers in dopaminergic neurons. Oligomeric GAPDH species with ability to interact with AS 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 molecular exclusion 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 species induced 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 molecular dynamics techniques.