Targeted covalent inhibition of disease-associated proteins has become a powerful methodology in the field of drug discovery, leading to the approval of new therapeutics. Nevertheless, current approaches are often limited owing to their reliance on a cysteine residue to generate the covalent linkage. Here we used aryl boronic acid carbonyl warheads to covalently target a noncatalytic lysine side chain, and generated to our knowledge the first reversible covalent inhibitors for Mcl-1, a protein-protein interaction (PPI) target that has proven difficult to inhibit via traditional medicinal chemistry strategies. These covalent binders exhibited improved potency in comparison to noncovalent congeners, as demonstrated in biochemical and cell-based assays. We identified Lys234 as the residue involved in covalent modification, via point mutation. The covalent binders discovered in this study will serve as useful starting points for the development of Mcl-1 therapeutics and probes to interrogate Mcl-1-dependent biological phenomena.
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We thank P. Ross for protein mass spectrometry assistance, E. Code and K. Jacques for advice and help for the preparation of Mcl-1 K234A mutant, A. Shapiro and J. Breen for discussion of the kinetic data obtained from time-dependent TR-FRET binding experiments, R. Chen for helpful discussions, and M. Vasbinder for proofreading the manuscript and helpful discussions. We thank the AstraZeneca PostDoc Program for funding this project.
All authors are current or former employees of AstraZeneca Pharmaceuticals.
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Akçay, G., Belmonte, M., Aquila, B. et al. Inhibition of Mcl-1 through covalent modification of a noncatalytic lysine side chain. Nat Chem Biol 12, 931–936 (2016). https://doi.org/10.1038/nchembio.2174
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