Molecular Mechanism of Cellular Oxidative Stress Sensing by Keap1

Cell Rep. 2019 Jul 16;28(3):746-758.e4. doi: 10.1016/j.celrep.2019.06.047.

Abstract

The Keap1-Nrf2 system plays a central role in the oxidative stress response; however, the identity of the reactive oxygen species sensor within Keap1 remains poorly understood. Here, we show that a Keap1 mutant lacking 11 cysteine residues retains the ability to target Nrf2 for degradation, but it is unable to respond to cysteine-reactive Nrf2 inducers. Of the 11 mutated cysteine residues, we find that 4 (Cys226/613/622/624) are important for sensing hydrogen peroxide. Our analyses of multiple mutant mice lines, complemented by MEFs expressing a series of Keap1 mutants, reveal that Keap1 uses the cysteine residues redundantly to set up an elaborate fail-safe mechanism in which specific combinations of these four cysteine residues can form a disulfide bond to sense hydrogen peroxide. This sensing mechanism is distinct from that used for electrophilic Nrf2 inducers, demonstrating that Keap1 is equipped with multiple cysteine-based sensors to detect various endogenous and exogenous stresses.

Keywords: Keap1; Nrf2; oxidative stress response; reactive cysteine residues.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cysteine / metabolism*
  • HEK293 Cells
  • Humans
  • Hydrogen Peroxide / metabolism*
  • Kelch-Like ECH-Associated Protein 1 / chemistry
  • Kelch-Like ECH-Associated Protein 1 / genetics*
  • Kelch-Like ECH-Associated Protein 1 / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mutation
  • NF-E2 Transcription Factor / genetics
  • NF-E2 Transcription Factor / metabolism
  • Oxidative Stress / genetics*
  • Oxidative Stress / physiology

Substances

  • KEAP1 protein, human
  • Keap1 protein, mouse
  • Kelch-Like ECH-Associated Protein 1
  • NF-E2 Transcription Factor
  • Hydrogen Peroxide
  • Cysteine