Protein Interaction Screening for E3 Ligase Target Discovery
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Solution Overview
Problem
Existing protein-protein interaction screening methods, such as phage display and yeast surface display, are limited in throughput, resolution, and ability to detect subtle modulations in binding affinity, making it difficult to identify novel substrates for E3 ubiquitin ligases and design effective small molecules for protein degradation.
Innovation Solution
A high-throughput method using recombinant haploid yeast cells to express and display libraries of ubiquitin ligase and substrate species, allowing for quantitative assessment of interactions and identification of modified pairs with enhanced or reduced binding affinities, enabling detection of novel substrate interactions and modulation by small molecules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phage display or yeast surface display is used for protein-protein interaction screening, then binding interactions can be detected, but throughput is limited and subtle affinity changes cannot be resolved
Solution Approach 1:
The patent replaces traditional mechanical/physical display methods (phage display, yeast surface display) with a chemical-based high-throughput screening approach using small molecules and affinity measurements, enabling both high throughput and precise detection of binding affinity changes
Solution Approach 2:
The patent changes the measurement parameters from qualitative binding detection to quantitative affinity measurement (Kd values), enabling detection of subtle affinity changes while maintaining high throughput through systematic variation of small molecule concentrations and measurement conditions
2Adaptability or versatility
If traditional small molecule inhibitors are designed, then target binding can be achieved, but inability to modulate protein-protein interactions limits effectiveness against undruggable targets
Solution Approach 1:
The patent introduces small molecules as intermediaries that bind to E3 ubiquitin ligases and induce conformational changes, thereby mediating the interaction between the ligase and target protein substrates to promote degradation of previously undruggable targets
Solution Approach 2:
The patent changes the mode of action from direct target inhibition to indirect modulation of protein-protein interactions, expanding the versatility of small molecule therapy to include previously undruggable targets while maintaining reliability through the natural protein degradation pathway
3Productivity
If PROTACs are used to induce protein degradation, then target degradation can be achieved, but high molecular weight and poor pharmaceutical properties make them unsuitable as drugs
Solution Approach 1:
The patent extracts the essential functional element from PROTACs—the small molecule component that binds E3 ligase and induces target degradation—while eliminating the complex bispecific antibody structure, thereby retaining degradation efficiency while improving drug suitability
Solution Approach 2:
The patent creates simplified copies of the PROTAC mechanism using small molecules that replicate the E3 ligase binding and target induction capability without the high molecular weight structure, achieving both degradation efficiency and pharmaceutical suitability
Data Source
AI summary
Provided herein are methods for identifying pairs of protein binding partners, mutations of which may inform the discovery of pharmaceutically useful small molecules. The methods disclosed herein may allow for the adaptation of the native protein degradation system to modulate specific disease targets at the protein level, in particular, for targets that have long been considered undruggable.