Crystal structure of the kelch domain of human keap1

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The transcription factor Nrf2 activates transcription of Phase II detoxification genes to combat oxidative stress. Under normal conditions, Nrf2 is located in the cytoplasm and is associated with a BTB-Kelch protein termed Keap1. Keap1 functions as a substrate adaptor and assembles with Nrf2 into a Cullin3-based E3 ubiquitin ligase complex to target Nrf2 for degradation. When cells are challenged with oxidative stress or exposed to chemopreventive reagents, Nrf2 is no longer degraded, but accumulates in the nucleus. Subsequent activation of Phase II genes helps cells to restore redox homeostasis. We have used a structural biology approach to investigate the interaction surface between Nrf2 and Keap1. Starting from a structural view at the atomic level, we hope to reveal in detail the interaction between the Neh2 domain and Kelch domain. The structure of the Kelch domain of human Keap1 has been determined to 1.35Å resolution. We further defined a Neh2-Kelch interface on the bottom side of the Kelch domain and crystallized a putative Kelch-Neh2 complex, which diffracts to 4Å.