Lipid-induced conformational changes in glyceraldehyde-3-phosphate dehydrogenase lead to tetramer dissociation and amyloid fibril formation

TORRES-BUGEAU, CLARISA MARÍA; CORTEZ, LEONARDO; AVILA, CESAR LUIS; FARIAS, RICARDO NORBERTO; MORERO, ROBERTO DIONISIO; CHEHIN, ROSANA

Los Cocos, Cordoba

Congreso; XXXVIII Reunion Anual de la Sociedad Argentina de Biofisica; 2009

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a multifunctional enzyme with cytoplasmic, membrane and nuclear activities apart from its traditional role in energy production. Moreover, GAPDH may also participate in Huntington’s, Parkinson’s and Alzheimer’s diseases. Despite the mechanism of amyloid fibril formation of this soluble enzyme has not been elucidated, the fact that membranes can trigger the process was demonstrated. In this paper, the structural changes and the aggregation kinetics of GAPDH undergone at pH 7.4 and 37ºC, right from its interaction with acidic membranes until the amyloid fibril is formed is reported. The aggregation kinetics showed a lag phase of about 10 min followed by a nucleation-dependent growth process common in amyloid fibril formation. Structural features of GAPDH before its interaction with membranes as well as during the lag and amyloid fibrils formation periods were studied by infrared spectroscopy. A significant increment in GAPDH solvent accessible area was observed upon protein-membrane interaction. The unambiguous identification of the oligomer-oligomer contact band in the infrared spectra allowed us to monitor the GAPDH tetramer dissociation. According to our results, the GAPDH-membrane binding induces a conformational change in the enzyme characterized by a b-structuration. To our knowledge, this is the first report demonstrating that GAPDH conformational changes induced by membrane binding leads to the tetramer dissociation with a consequent exposure of new surfaces to trigger the amyloid fibrillation process.