# Determine the mechanism of recognition of ubiquitin configurations by the 26S proteasome

> **NIH NIH R01** · HARVARD MEDICAL SCHOOL · 2021 · $348,822

## Abstract

Project Summary/Abstract
 The ubiquitin-proteasome system is the major pathway for regulatory protein degradation, exhibiting a
similar level of target specificity as translation/translation underlying most biological functions. Ubiquitin
patterns on substrate molecules determine the specificity, the rate and the outcome of proteolysis by the
proteasome. Which features of ubiquitin configurations are important for the selectivity of proteasomal
degradation and how the 26S proteasome, with a multitude of ubiquitin receptors, recognizes these features is
still poorly understood. Proteasomal degradation involves a sequence of steps. Our published and preliminary
studies recorded a strong dependence of the degradation rate on the length, linkage, copy-number and
position of conjugated ubiquitin chains. How this selectivity is achieved is still unclear. Here, I propose a
systematic investigation to identify how the features of ubiquitin configurations control the kinetics and modes
of substrates’ engagement with the ubiquitin receptors on proteasome to determine the rate of degradation.
We will employ a single-molecule method I developed previously to differentiate multiple limiting steps in the
degradation process and to measure their rate constants. To circumvent the difficulty with preparing protein
substrates with defined ubiquitylation, I propose a novel method of using DNA scaffolds to engineer arbitrary
yet defined ubiquitin configurations, and systematically vary the features of ubiquitin configuration to determine
how they affect substrate’s interaction with proteasome and degradation. Dysregulation of the ubiquitin-
proteasome system is implicated in numerous diseases, including cancers, neurodegenerative disorders,
autoimmunity and diabetes. The long-term goal of our lab is to elucidate how the proteasome recognizes its
targets and selectively engages them into the processive degradation process, and to understand how
misregulation of protein degradation leads to the formation of pathogenic inclusions. Our proposed research
will provide insights into how mutations in the ubiquitin conjugation pathways lead to human diseases, and will
generate valuable information for developing novel therapeutic strategies.

## Key facts

- **NIH application ID:** 10248431
- **Project number:** 5R01GM134064-03
- **Recipient organization:** HARVARD MEDICAL SCHOOL
- **Principal Investigator:** Ying Lu
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $348,822
- **Award type:** 5
- **Project period:** 2019-09-15 → 2024-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10248431

## Citation

> US National Institutes of Health, RePORTER application 10248431, Determine the mechanism of recognition of ubiquitin configurations by the 26S proteasome (5R01GM134064-03). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10248431. Licensed CC0.

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