Human sirtuins are differentially sensitive to inhibition by nitrosating agents and other cysteine oxidants.

Sirtuins ( human Sirt1-7) catalyze the removal of acyl groups from lysine residues in proteins in an NAD-dependent manner, and loss of sirtuin deacylase activity correlates with the development of aging-related diseases. Although multiple reports suggest that sirtuin activity is regulated by oxidative post-translational modifications of cysteines during inflammation and aging, no systematic comparative study of potential direct sirtuin cysteine oxidative modifications has been performed. Here, using IC and / analyses, we quantified the ability of nitrosothiols (-nitrosoglutathione and -nitroso--acetyl-d,l-penicillamine), nitric oxide, oxidized GSH, and hydrogen peroxide to post-translationally modify and inhibit the deacylase activity of Sirt1, Sirt2, Sirt3, Sirt5, and Sirt6. The inhibition was correlated with cysteine modification and assessed with chemical-probe and blot-based assays for cysteine -nitrosation, sulfenylation, and glutathionylation. We show that the primarily nuclear sirtuins Sirt1 and Sirt6, as well as the primarily cytosolic sirtuin Sirt2, are modified and inhibited by cysteine -nitrosation in response to exposure to both free nitric oxide and nitrosothiols (/ ≥ 5 m s), which is the first report of Sirt2 and Sirt6 inhibition by -nitrosation. Surprisingly, the mitochondrial sirtuins Sirt3 and Sirt5 were resistant to inhibition by cysteine oxidants. Collectively, these results suggest that nitric oxide-derived oxidants may causatively link nuclear and cytosolic sirtuin inhibition to aging-related inflammatory disease development.