Evolutionary conserved N-terminal domain of Nrf2 is essential for the Keap1-mediated degradation of the protein by proteasome

Under homeostatic conditions, Nrf2 activity is constitutively repressed. This process is dependent on Keap 1, to which Nrf2 binds through the Neh2 domain. Since the N-terminal subdomain of Neh2 (Neh2-NT) contains evolutionarily conserved motifs, we examined the roles they play in the degradation of Nrf2. In Neh2-NT, we defined a novel motif that is distinct from the previously characterized DIDLID motif and designated it DLG motif. Deletion of Neh2-NT or mutation of the DEG motif largely abolished the Keap 1-mediated degradation of Nrt2. These mutations were found to enfeeble the binding affinity of Nrf2 to Keap 1. The Neh2-NT subdomain directed DLG-dependent, Keap 1-independent, degradation of a reporter protein in the nucleus. By contrast, mutation of DLG did not affect the half-life of native Nrt2 protein in the nucleus under oxidative stress conditions. These results thus demonstrate that DEG motif plays essential roles in the Keap 1-mediated proteasomal degradation of Nrf2 in the cytoplasm. (C) 2004 Elsevier Inc. All rights reserved.