Harnessing sulfinic acid reactivity to report protein S‐nitrosylation (968.2)

Abstract

Oxidative stress describes the accumulation of reactive oxygen (ROS) and reactive nitrogen species (RNS), and is a hallmark of neurodegeneration and cancer. Cysteine residues can be oxidized by nitric oxide to nitrosocysteine (RSNO) or by peroxide to a sulfinic acid (RSO2H). We find that sulfinic acids react with nitrosothiols to form a thiosulfonate linkage. Using sulfinic acid‐linked probes, we demonstrate selective enrichment and mass spectrometry annotation of more than 1500 endogenous S‐nitrosylated proteins. This list includes nearly all previously annotated S‐nitrosylated proteins, including ion channels, chaperones, peroxiredoxins, p53, HDACs, hundreds of metabolic enzymes, as well as a rich set of novel proteins. Interestingly, the familial PD gene DJ‐1 protects cells from oxidative stress, and requires oxidation of an evolutionarily conserved cysteine to a sulfinic acid. Furthermore, high‐resolution mass spectrometry analysis and chemiluminescence NO detection confirms that S‐nitroso‐cysteine reacts with oxidized DJ‐1, causing elimination of nitric oxide. Furthermore, we discuss novel strategies to annotate and profile protein sulfinylation using orthogonal reactive probes. Based on these findings, we propose that sulfinic acids, such as in DJ‐1, function to reduce nitrosative stress, establishing a novel mechanism of redox regulation. Support is provided from the University of Michigan.