Bidirectional regulation of KEAP1 BTB domain-based sensor activity

Area of Science:

• Biochemistry
• Molecular Biology
• Cellular Biology

Background:

• The KEAP1-CUL3 ubiquitin ligase complex is crucial for regulating the stability of the NRF2 transcription factor, playing a key role in cellular stress responses.
• The BTB domain of KEAP1 acts as a sensor for electrophilic compounds, but the exact mechanisms of electrophile recognition and inhibition of BTB activity are not fully understood.

Purpose of the Study:

• To elucidate the molecular mechanisms by which electrophilic modifications regulate the activity of the KEAP1 BTB domain.
• To investigate how electrophiles alter the spatial arrangement of the BTB homodimer and affect KEAP1-CUL3 ligase activity.

Main Methods:

• Co-crystal structural analyses of the KEAP1 BTB domain.
• Functional studies using NRF2-inducing CDDO-derivatives and synthetic electrophilic compounds.
• Investigation of the role of Cys151 in electrophile sensing and regulation of KEAP1-CUL3 complex affinity.

Main Results:

• Electrophilic modification induces changes in the spatial arrangement of the KEAP1 BTB homodimer, impacting its ligase activity.
• Modification of Cys151 by NRF2 inducers alters the CUL3-binding sites, reducing KEAP1-CUL3 complex affinity.
• A Cys151-targeting NRF2 inhibitor causes an opposite rearrangement of the BTB homodimer.

Conclusions:

• The study reveals the precise molecular mechanism by which the KEAP1 BTB domain senses electrophiles and regulates KEAP1-CUL3 ubiquitin ligase activity.
• Understanding this mechanism provides insights into cellular stress response pathways and potential therapeutic strategies involving NRF2 modulation.