Molecular Basis for Redox Activation of Epidermal Growth Factor Receptor Kinase

Epidermal growth factor receptor (EGFR) is a target of signal-derived H2O2, and oxidation of active-site cysteine 797 to sulfenic acid enhances kinase activity. Although a major class of covalent drugs targets C797, nothing is known about its catalytic importance or how S-sulfenylation leads to activation. Here, we report the first detailed functional analysis of C797. In contrast to prior assumptions, mutation of C797 diminishes catalytic efficiency in vitro and cells. The experimentally determined pKa and reactivity of C797 toward H2O2 correspondingly distinguish this residue from the bulk of the cysteinome. Molecular dynamics simulation of reduced versus oxidized EGFR, reinforced by experimental testing, indicates that sulfenylation of C797 allows new electrostatic interactions to be formed with the catalytic loop. Finally, we show that chronic oxidative stress yields an EGFR subpopulation that is refractory to the FDA-approved drug afatinib. Collectively, our data highlight the significance of redox biology to understanding kinase regulation and drug pharmacology. [Display omitted] •The EGFR active-site cysteine (C797) is a target of NADPH oxidase-derived H2O2•Unique biochemical properties distinguish C797 within the cysteine proteome•C797 sulfenylation allows new electrostatic interactions with the catalytic loop•Chronic oxidative stress yields an EGFR population that is refractory to afatinib Truong et al. elucidate the molecular mechanism underlying redox activation of EGFR. Sulfenylation of C797 activates EGFR kinase through new electrostatic interactions, which may induce a favorable change in catalytic loop dynamics. Furthermore, C797 sulfenylation and H2O2 stress affects the pharmacology of covalent, thiol-targeted EGFR inhibitors.