Aberrant Post-translational Modifications (PTMs) in Methyl- and Propionic Acidemia and the Construction of a Novel Sirtuin (SIRT) Gene to Metabolize PTMs

Isolated Methylmalonic Acidemia (MMA) and the related disorder Propionic Acidemia (PA) comprise a relatively common and heterogeneous group of inborn errors of metabolism. NHGRI scientist discovered that in isolated MMA, a novel inhibitory PTM, methylmalonyllysine, is generated and inactivates protein targets through the failure of SIRT-mediated deacylation, and identified a series of antibodies for PTM specificity. A novel acylation resistant SIRT5 was created that did not exhibit enzymatic inhibition after hyper-methylmalonylation and appears to be resistant to inhibition by nicotinamide, which may be a universal therapy for all forms of MMA and PA. The scientist also developed a new assay involving sirtuin modulation, for targeted therapies that might be widely applicable to all forms of MMA as well as other the larger group of organic acidemias and fatty acid oxidation disorders where acyl-CoA accretion occurs. The new assays will be useful to develop small molecules that stimulate removal of methylmalonyl- and propionyl- groups for novel therapies.