Crystal structures of DCAF1-PROTAC-WDR5 ternary complexes provide insight into DCAF1 substrate specificity

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• Proteolysis-targeting chimeras (PROTACs) leverage E3 ubiquitin ligases for targeted protein degradation.
• Limited E3 ligase substrate receptors hinder PROTAC development, as their downregulation or mutation impacts efficacy.
• DCAF1, a substrate receptor for EDVP and CUL4 E3 ligases, presents a promising alternative.

Purpose of the Study:

• To develop novel DCAF1-based PROTACs targeting WDR5, a significant protein in various cancers.
• To investigate the degradation efficacy of these DCAF1-WDR5 PROTACs.
• To elucidate the structural basis of DCAF1-PROTAC-WDR5 interactions.

Main Methods:

• Design and synthesis of four DCAF1-based PROTACs.
• Assessment of endogenous and exogenous WDR5 degradation.
• High-resolution crystal structure determination of DCAF1-PROTAC-WDR5 ternary complexes.

Main Results:

• Four DCAF1-based PROTACs demonstrated effective degradation of WDR5.
• Crystal structures revealed detailed interactions between DCAF1, PROTACs, and WDR5.
• DCAF1 loops were identified as crucial for substrate recognition and conformational flexibility.

Conclusions:

• DCAF1 is a viable substrate receptor for developing PROTACs against cancer targets like WDR5.
• The structural insights provide a mechanistic understanding of DCAF1's role in substrate recruitment.
• This work expands the toolkit for PROTAC-mediated protein degradation.