The Scripps Research Institute

Keriann M Backus

Benjamin F Cravatt

Megan Blewett

Chu Wang

Bruno E Correia

John R Teijaro

Cells produce electrophilic products with the potential to modify and affect the function of proteins. Chemoproteomic methods have provided a means to qualitatively inventory proteins targeted by endogenous electrophiles; however, ascertaining the potency and specificity of these reactions to identify the most sensitive sites in the proteome to electrophilic modification requires more quantitative methods. Here, we describe a competitive activity-based profiling method for quantifying the reactivity of electrophilic compounds against 1000+ cysteines in parallel in the human proteome. Using this approach, we identify a select set of proteins that constitute hot spots for modification by various lipid-derived electrophiles, including the oxidative stress product 4-hydroxnonenal (HNE). We show that one of these proteins, ZAK kinase, is labeled by HNE on a conserved, active site-proximal cysteine, resulting in enzyme inhibition to create a negative feedback mechanism that can suppress the activation of JNK pathways by oxidative stress.

Cysteine-reactive ligand discovery in proteomes

Disclosed herein are methods, compositions, probes, polypeptides, assays, and kits for identifying a cysteine containing protein as a binding target for a small molecule fragment. Also disclosed herein are methods, compositions, and probes for mapping a biologically active cysteine site on a protein and screening a small molecule fragment for interaction with a cysteine containing protein.

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La Jolla, CA, United States of America

Keriann M Backus