Characterizations of three major cysteine sensors of Keap1 in stress response

Ryota Saito, Takafumi Suzuki, Keiichiro Hiramoto, Soichiro Asami, Eriko Naganuma, Hiromi Suda, Tatsuro Iso, Hirotaka Yamamoto, Masanobu Morita, Liam Baird, Yuki Furusawa, Takaaki Negishi, Masakazu Ichinose, Masayuki Yamamoto

Research output: Contribution to journalArticlepeer-review

180 Citations (Scopus)


The Keap1-Nrf2 system plays a central role in cytoprotection against electrophilic/oxidative stresses. Although Cys151, Cys273, and Cys288 of Keap1 are major sensor cysteine residues for detecting these stresses, it has not been technically feasible to evaluate the functionality of Cys273 or Cys288, since Keap1 mutants that harbor substitutions in these residues and maintain the ability to repress Nrf2 accumulation do not exist. To overcome this problem, we systematically introduced amino acid substitutions into Cys273/Cys288 and finally identified Cys273Trp and Cys288Glu mutations that do not affect Keap1's ability to repress Nrf2 accumulation. Utilizing these Keap1 mutants, we generated stable murine embryonic fibroblast (MEF) cell lines and knock-in mouse lines. Our analyses with the MEFs and peritoneal macrophages from the knock-in mice revealed that three major cysteine residues, Cys151, Cys273, and Cys288, individually and/or redundantly act as sensors. Based on the functional necessity of these three cysteine residues, we categorized chemical inducers of Nrf2 into four classes. Class I and II utilizes Cys151 and Cys288, respectively, while class III requires all three residues (Cys151/Cys273/Cys288), while class IV inducers function independently of all three of these cysteine residues. This study thus demonstrates that Keap1 utilizes multiple cysteine residues specifically and/or collaboratively as sensors for the detection of a wide range of environmental stresses.

Original languageEnglish
Pages (from-to)271-284
Number of pages14
JournalMolecular and cellular biology
Issue number2
Publication statusPublished - 2016

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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