Yeast Surface Display for High-Affinity Antibody Selection
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Solution Overview
Problem
Current methods for displaying and screening recombinant proteins, such as phage display, face limitations including the inability to perform post-translational modifications like glycosylation, difficulties in discriminating high-affinity antibodies, and issues with reproducibility and specificity due to bacterial expression systems, which hinder the development of antibodies with sub-nanomolar affinity and specificity.
Innovation Solution
A method for expressing and displaying proteins on the surface of lower eukaryotes like yeast using genetic fusion of cell surface anchoring proteins with adapter peptides, allowing for the selection of proteins with desirable binding properties through fluorescence-activated cell sorting (FACS) and controlled glycosylation, mimicking cell surface display of antibodies by B cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phage display is used for antibody screening, then library construction and screening capability are improved, but the ability to perform post-translational modifications like glycosylation is lost
Solution Approach 1:
The patent uses yeast cells as an intermediary expression system between bacterial phage display and mammalian cell systems. Yeast provides eukaryotic post-translational modification capabilities (glycosylation, disulfide bond formation) while still enabling high-throughput library construction and screening, thus mediating the trade-off between productivity and adaptability
Solution Approach 2:
The patent changes the expression system parameter from prokaryotic (E. coli/phage) to eukaryotic (yeast), which fundamentally alters the post-translational modification capabilities while maintaining the ability to conduct combinatorial library screening. This parameter change enables both glycosylation and high-throughput screening simultaneously
2Measurement precision
If panning is used to select high-affinity antibodies, then binding affinity selection is improved, but discrimination of very high affinity antibodies (Kd≤1 nM) becomes difficult due to harsh elution conditions
Solution Approach 1:
The patent replaces the mechanical/chemical panning method with fluorescence-activated cell sorting (FACS). FACS uses fluorescent labeling and flow cytometry to detect and sort cells based on binding affinity, eliminating the need for harsh chemical elution conditions while maintaining the ability to select high-affinity antibodies with Kd≤1 nM
Solution Approach 2:
The patent employs fluorescent labels that emit different colors or intensities based on binding events. This color/fluorescence signal change enables non-destructive detection of antibody-antigen binding affinity, allowing discrimination of very high affinity antibodies without requiring harsh elution that would denature the phage particle
3Ease of manufacture
If physical immobilization of antigen to solid surface is used, then panning process is simplified, but avidity effects mask true affinity and reproducibility is reduced
Solution Approach 1:
The patent replaces physical immobilization of antigen on solid surfaces with soluble antigen presentation on yeast cell surfaces. This substitution eliminates avidity effects caused by multi-site binding to immobilized antigen while maintaining a simplified high-throughput screening process through FACS, thereby improving measurement precision without sacrificing ease of manufacture
Solution Approach 2:
The patent uses yeast cells as a mobile copy or surrogate for solid-phase antigen presentation. The yeast cell surface displays soluble antigen in a physiological context, copying the benefits of immobilized antigen screening while avoiding the drawbacks of solid-phase avidity effects and entropic penalties, thus improving affinity measurement accuracy
4Ease of operation
If bacterial expression systems are used, then ease of manipulation and growth is improved, but specificity and reproducibility of antibody binding are reduced
Solution Approach 1:
The patent changes the expression system parameter from prokaryotic (bacterial) to eukaryotic (yeast), which introduces proper post-translational modifications (glycosylation, disulfide bonds) that are critical for antibody structure and function. This parameter change maintains ease of manipulation and growth while significantly improving antibody binding specificity and reproducibility
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
Enables the efficient selection and production of antibodies with high affinity and specificity by overcoming the limitations of bacterial systems, facilitating the development of antibodies for therapeutic applications like cancer therapy and tumor imaging.
Implementation Method 1
a first adapter peptide capable of pairwise binding to a second adapter peptide
Implementation Method 2
selected by fluorescence-activated cell sorting (FACS)
Data Source
AI summary
Methods for display of recombinant proteins or protein libraries on the surface of lower eukaryotes such as yeast and filamentous fungi are described. The methods are useful for screening libraries of recombinant proteins in lower eukaryotes to identify particular proteins with desired properties from the array of proteins in the libraries. The methods are particularly useful for constructing and screening antibody libraries in lower eukaryotes.