ByeTAC: Bypassing E-Ligase-Targeting Chimeras for Direct Proteasome Degradation

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• Targeted protein degradation is a powerful therapeutic strategy.
• Current methods rely on E3 ligases, limiting applications to ubiquitinate-ready proteins.
• Developing new degradation pathways is crucial for expanding therapeutic potential.

Purpose of the Study:

• To introduce a new methodology for targeted protein degradation.
• To overcome limitations of E3 ligase-dependent degradation.
• To demonstrate direct recruitment of proteins to the proteasome for degradation.

Main Methods:

• Designed bifunctional molecules (ByeTACs) linking a small molecule ligand to a 26S proteasome subunit.
• Utilized Rpn-13, a nonessential ubiquitin receptor of the 26S proteasome, for recruitment.
• Demonstrated degradation of target proteins independent of the E3 ligase cascade.

Main Results:

• Successfully generated ByeTACs for targeted protein degradation.
• ByeTACs mediate degradation by binding to Rpn-13 and the protein of interest.
• Degradation occurs without requiring the endogenous ubiquitination pathway.

Conclusions:

• The ByeTAC methodology offers a new approach for targeted protein degradation.
• Direct recruitment to the proteasome via Rpn-13 bypasses E3 ligase dependency.
• This strategy broadens the scope of proteasome-mediated degradation for therapeutic applications.