High-Throughput Assay for Characterizing Rpn11 Deubiquitinase Activity
Gang Xie1,2, Ken C Dong1,2,3, Evan J Worden4
1Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA, USA.
Methods in Molecular Biology (Clifton, N.J.)
|November 9, 2022
Summary
Rpn11, a proteasome component, removes ubiquitin chains. Researchers developed a new assay to measure its deubiquitinase (DUB) activity, enabling the discovery of Rpn11-targeted cancer drugs.
Area of Science:
- Biochemistry
- Molecular Biology
- Proteasome Biology
Background:
- Rpn11 is a metalloprotease crucial for the 26S proteasome's function in protein degradation.
- Its deubiquitinase (DUB) activity is mechanically stimulated by substrate translocation into the proteasomal motor.
- Unlike other DUBs, Rpn11 lacks selectivity for specific ubiquitin-chain linkages.
Purpose of the Study:
- To develop a robust biochemical assay for measuring Rpn11 DUB activity.
- To enable high-throughput screening for small-molecule inhibitors targeting Rpn11.
- To facilitate the development of novel anticancer therapeutics targeting the proteasome.
Main Methods:
- Purification of the Rpn8/Rpn11 heterodimer.
- Synthesis of a model substrate, ubiquitin-GC-TAMRA.
- Characterization of Rpn11 DUB activity in isolation.
Main Results:
- A method to measure Rpn11 DUB activity without 26S proteasomes was established.
- The assay utilizes purified Rpn8/Rpn11 and ubiquitin-GC-TAMRA.
- This facilitates Rpn11-targeted drug discovery.
Conclusions:
- The developed assay provides a platform for high-throughput screening of Rpn11 inhibitors.
- Targeting Rpn11 offers a promising strategy for anticancer drug development.
- This research advances the understanding of proteasomal deubiquitination mechanisms.
