NAD+ inhibit GAPDH aggregation by preventing nitrosative stress-induced conformational changes

MUÑOZ SOSA, CHRISTIAN J.; ROMERO, JORGE M.; CURTINO, JUAN A.; CARRIZO, MARÍA E.

Congreso; LIV Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2018

Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB)

Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is a multifunctional protein involved in cell death processes frequently associated with oxidative/nitrosative stress. S-nitrosylation of GAPDH facilitates its binding to the E3-ubiquitin-ligase Siah1, which has a nuclear localization signal that promotes the entrance of the protein complex to the nucleus causing apoptosis. GOSPEL (GAPDH´s Competitor Of Siah1 Protein Enhances Life) protein interacts with GADPH and interferes with the binding between GAPDH and Siah1, inhibiting their apoptotic effect.Oxidative/nitrosative stress also induces the aggregation of GAPDH in vitro, which is in accordance with the presence of the enzyme in insoluble aggregates found in some neurodegenerative diseases.Evidence provided by our laboratory indicates that in the presence of nitric oxide (NO) GOSPEL co-aggregates with GAPDH increasing its aggregation rate. GAPDH Cys152 plays an essential role in this process since their S-nitrosylation initiates the oxidative modification that triggers the formation of disulfide-bonded aggregates. Both GAPDH aggregation and GAPDH-GOSPEL co-aggregation were inhibited by NAD+.Here we present preliminary circular dichroism studies indicating that NAD+ inhibits the conformational changes induced by the NO donor NOR3. We also report the X-ray structure of GAPDH treated with NOR3 in the presence of NAD+. Its analysis showed that in addition to the NAD+ density the difference map exhibits a positive density connected to the SH of Cys152 that could only be attributed to NO. These results suggest that NAD+ could be inhibiting the NOR3-induced aggregation by stabilizing NO-GAPDH conformation.