Cysteine residues play diverse functional roles in proteins, including catalysis, metal-binding, structural stabilization and redox regulation. These functional cysteines are highly reactive and can be targeted by electrophilic small molecules. We have applied a chemical-genetics strategy to identify covalent small-molecule modifiers for a diverse array of cysteines within human proteomes. These covalent modulators were identified from in-house small-molecule libraries based on triazine, piperidine and peptide-based scaffolds. All compounds contain a cysteine-reactive electrophile for covalent modification, a diversity element to direct the small-molecules toward distinct subsets of the proteome, and an alkyne as a bio-orthogonal click-chemistry handle for downstream target identification. Through phenotypic screening, we have identified selective and potent covalent modifiers for diverse proteins including beta-tubulin, glutathione S-transferase omega and protein disulphide isomerase. Our studies illustrate the potential of irreversible cysteine-targeted inhibitors as pharmacological agents for a large subsection of the proteome and the utility of click chemistry to enable target identification within a complex proteome. More recently, we have expanded our studies to identify electrophiles that target other nucleophilic amino acids, such as tyrosine and lysine, for incorporation into small-molecule scaffolds. As before, click chemistry has enabled the identification of the protein targets and the exact site of modification for these electrophilic small molecules.<br/>

Chemical-genetics strategy to identify covalent cysteine-reactive small molecules

251st National Meeting (2016)

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