The sirtuin enzymes are important regulatory deacylases in a variety of biochemical contexts and may therefore be potential therapeutic targets through either activation or inhibition by small molecules. Here, we describe the discovery of the most potent inhibitor of sirtuin 5 (SIRT5) reported to date. We provide rationalization of the mode of binding by solving co-crystal structures of selected inhibitors in complex with both human and zebrafish SIRT5, which provide insight for future optimization of inhibitors with more “drug-like” properties. Importantly, enzyme kinetic evaluation revealed a slow, tight-binding mechanism of inhibition, which is unprecedented for SIRT5. This is important information when applying inhibitors to probe mechanisms in biology.

We discovered that the survival and growth of many primary acute myeloid leukemia (AML) samples and cell lines, but not normal CD34 + cells, are dependent on SIRT5, a lysine deacylase implicated in regulating multiple metabolic pathways. Dependence on SIRT5 is genotype agnostic and extends to RAS-and p53-mutated AML. Results were comparable between SIRT5 knockdown and SIRT5 inhibition using NRD167, a potent and selective SIRT5 inhibitor. Apoptosis induced by SIRT5 disruption is preceded by reductions in oxidative phosphorylation and glutamine utilization, and an increase in mitochondrial superoxide that is attenuated by ectopic superoxide dismutase 2. These data indicate that SIRT5 controls and coordinates several key metabolic pathways in AML and implicate SIRT5 as a vulnerability in AML.SIgnIfIcAnce: Reducing SIRT5 activity is detrimental to the survival of AML cells regardless of genotype, yet well tolerated by healthy hematopoietic cells. In mouse models, disrupting SIRT5 inhibits AML progression. SIRT5 controls several metabolic pathways that are required for leukemia cell survival. These results identify SIRT5 as a therapeutic target in AML.

No abstract

Sirtuin 2 (SIRT2) is a protein deacylase enzyme that removes acetyl groups and longer chain acyl groups from post-translationally modified lysine residues. Here, we developed small peptide-based inhibitors of its activity in living cells in culture.

The sirtuin enzymes are potential drug targets for intervention in a series of diseases. Efforts to inhibit enzymes of this class with thioamide-and thiourea-containing, substrate-mimicking entities have produced a number of high-affinity binders. However, less attention has been dedicated to the investigation of the stability of these inhibitors under various conditions. Here, we provide evidence of unprecedented degree of cleavage of short-chain e-N-thioacyllysine modifications meant to target these sirtuins and further provide insights into the serum stability of compounds containing both thioamides and thioureas. Our study questions the utility short-chain thioamide-based inhibitors of sirtuins for drug development and points to mono-alkylated thiourea-based chemotypes as being more stable in human serum.