“Glyceraldehide-3-phosphate dehydrogenase amyloid folding pathway studied by infrared spectroscopy”

CHEHÍN ROSANA

Marecias (Sao Paolo)

Congreso; 3rd Internacional Workshop on Spectroscopy for Biology; 2010

Glyceraldehyde-3-phosphate dehydrogenase amyloid folding pathway studied by infrared spectroscopy Clarisa M. Torres-Bugeau1; Leonardo M. Cortez1, César Ávila1; Roberto Morero1, Ricardo Farías1 and Rosana N. Chehín1 1Departamento de Bioquímica de la Nutrición, Instituto Superior de Investigaciones Biológicas (INSIBIO) and Insitituto de Química Biológica Dr Bernabé Bloj (CONICET-UNT) Chacabuco 461 (T4000ILI) Tucumán, Argentina. e-mail:rosana@fbqf.unt.edu.ar Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a well-studied protein for its role in cellular energy production as a glycolytic enzyme. However, current evidences reveal that this enzyme is a multifunctional protein displaying a number of diverse cellular functions unrelated to glycolysis. GAPDH have been also implicated in some neuronal diseases since the enzyme was found with alpha-synuclein in the Lewy bodies of Parkinson´ s as well as in the Alzheimer senile plaque, indicating that GAPDH might play a role in the progression of these diseases. At physiological conditions of pH and temperature, GAPDH is capable to undergo strong conformational changes from globular soluble to amyloid structure when they interact with membranes containing anionic phospholipids. The GAPDH fibrillation could be also triggered by the presence of Glycosaminoglycans (GAGs) which are routinely found associated with amyloid deposits . In fact, Heparin increases dramatically the aggregation rate as well as the yield of GAPDH amyloid fibril formation. At the present, experimental evidence strongly suggests that the prefibrillar oligomeric aggregates are the cytotoxic species. However, the isolation and characterization of these aggregation intermediates is difficult due to they are transient. In order to obtain a full picture of the protein structural changes during aggregation process, in the present work we used infrared and fluorescent spectroscopy to identification and characterize the conformational intermediary’s species and oligomeric prefibrilar structures adopted by the polypeptide chain of GAPDH during the amyloid aggregation process induced by the presence of acidic membranes or glycosaminoglycans. According to our results, the GAPDH fibrillation process occurs upon the tetramer dissociation with the exposition of new surfaces to trigger the amyloid fibrillation process.