NAD+ inhibits GAPDH aggregation by preventing the nitrosative stress-induced conformational changes.

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

Paraná

Congreso; LIV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2018

Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is a multifunctional protein involved in cell death processes frequently associated withoxidative/nitrosative stress. S-nitrosylation of GAPDH facilitates its binding to the E3-ubiquitin-ligase Siah1, which has a nuclear localizationsignal that promotes the entrance of the protein complex to the nucleus causing apoptosis. GOSPEL (GAPDH's Competitor Of Siah1 ProteinEnhances 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 insolubleaggregates 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 Snitrosylation initiates the oxidative modification that triggers the formation of disulfide-bonded aggregates. Both GAPDH aggregation andGAPDH-GOSPEL co-aggregation were inhibited by NAD. Here we present preliminary circular dichroism studies indicating that NAD+ inhibitsthe conformational changes induced by the NO donor NOR3. We also report the X-ray structure of GAPDH treated with NOR3 in the presenceof NAD+. The analysis shows that in addition to the NAD+ density the difference map exhibits a positive density connected to the SH ofCys152 that could only be attributed to NO. These results suggest that NAD+ could be inhibiting the NOR3-induced aggregation by stabilizingNO-GAPDH conformation