E3-Binding Peptide Screening via Test Protein Degradation
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Solution Overview
Problem
Current PROTAC technologies are limited by their use of a restricted subset of E3 ligases, primarily from the RING family, failing to exploit the full potential of E3 ligases for targeted protein degradation, and there is a need to identify new E3 binding moieties to expand therapeutic applications.
Innovation Solution
A functional screening method is developed to identify peptides capable of binding to ubiquitin protein ligases (E3) by providing candidate peptides functionally linked to a test protein in eukaryotic cells, detecting the amount of test protein, and identifying peptides that reduce its presence, indicating E3 binding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If PROTAC technology uses a restricted subset of E3 ligases (primarily RING family), then the technology can be implemented with currently known E3 ligases, but the utility and therapeutic potential are limited
Solution Approach 1:
The patent introduces an intermediary screening system using eukaryotic cells expressing test proteins and candidate peptides. This intermediary system mediates the identification of E3-binding peptides by creating a functional linkage between the test protein and E3 ligases, enabling indirect detection of binding interactions without requiring direct manipulation of E3 ligase structures
Solution Approach 2:
The screening method employs self-service by utilizing the cell's own ubiquitination machinery and proteasomal degradation system. The endogenous E3 ligases within the eukaryotic cells automatically perform ubiquitination on candidate peptides that bind to test proteins, and the proteasome subsequently degrades the ubiquitinated complexes, providing a self-amplifying detection signal without external intervention
2Reliability
If only a limited number of known E3 ligases are used in PROTAC design, then the development process is simpler, but degradation efficiency and selectivity are suboptimal
Solution Approach 1:
The patent segments the E3 ligase interaction problem into discrete peptide units. By creating libraries of candidate peptides (7-110 amino acids) that can be individually tested, the system divides the complex task of identifying E3 binders into manageable segments, allowing systematic screening and selection of optimal peptide-E3 combinations
Solution Approach 2:
The screening method utilizes parameter changes in protein degradation levels as the readout mechanism. By measuring changes in test protein abundance (a quantifiable parameter) after exposure to candidate peptides, the system translates complex molecular binding events into measurable parameter changes that indicate successful E3 ligase recruitment
3Adaptability or versatility
If the full range of E3 ligase families (HECT, U-box, multi-subunit) is targeted, then therapeutic applications are expanded, but identification of binding peptides becomes more difficult
Solution Approach 1:
The patent creates a universal screening platform that can identify binding peptides for diverse E3 ligase families (HECT, U-box, multi-subunit, and RING). The standardized assay system using eukaryotic cells, test proteins, and ubiquitination machinery serves multiple functions: it detects binding for different E3 families, provides quantitative degradation readouts, and enables comparative analysis across E3 types without requiring family-specific detection methods
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the identification of new E3-binding peptides, potentially enhancing therapeutic efficacy by exploiting a broader range of E3 ligases and allowing targeted degradation of specific proteins in various tissues and cell types.
Implementation Method 1
under conditions enabling ubiquitination of proteins by an E3
Implementation Method 2
Proteins and/or peptides are targeted for degradation by adding ubiquitin to the target proteins and/or peptide
Data Source
AI summary
The present invention relates to a method of screening for peptides capable of binding to a ubiquitin protein ligase (E3), successful binding being determined by detecting the amount of a test protein in the cell. The invention relates to a method for determining if a peptide binds or is capable of binding to a ubiquitin protein ligase (E3) and thereby leads to degradation of a test protein, wherein the peptide is between about 7 and 110 amino acids in length, the method comprising: providing in a eukaryotic cell a candidate peptide functionally linked to a test protein, under conditions enabling ubiquitination of proteins by an E3; and detecting the amount of test protein present in the cell; whereby, a reduced amount of the test protein determines the candidate peptide as a peptide that binds or is capable of binding to an E3 (an E3-binding peptide).