Antibody Variable Domain Library Generation via Framework Diversification
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Solution Overview
Problem
Existing methods for generating antibody libraries struggle to produce diverse and structurally stable antibody variable domains, limiting the isolation of high-affinity binders and large-scale production due to inefficiencies in folding and diversity constraints.
Innovation Solution
The approach involves systematically generating polypeptides with diversified framework regions (VFR) and complementary determining regions (CDRs) by limiting diversity at structural amino acid positions and varying nonstructural positions, using specific codon sets to encode variant amino acids, thereby creating high-quality binders that are well-folded and adaptable for large-scale production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If diversity is generated through recombination of V, D and J segments, then antigen specificity is improved, but structural stability of the antibody variable domain deteriorates
Solution Approach 1:
The patent applies local quality by differentiating between CDR regions (high diversity allowed) and framework regions (structural constraints maintained). The framework regions are designed with specific amino acid compositions that preserve structural stability while CDR regions are diversified for antigen specificity. This localized differentiation resolves the contradiction by allowing diversity where needed without compromising structural integrity.
Solution Approach 2:
The patent utilizes parameter changes by systematically varying amino acid sequences at specific positions in the CDR regions while maintaining conserved framework sequences. This controlled parameter variation (amino acid sequence) in specific regions allows generation of diverse antigen binders while preserving overall structural stability through conserved framework parameters.
2Adaptability or versatility
If all CDR positions are diversified to maximize antigen binding diversity, then antigen binding diversity is improved, but structural perturbations increase
Solution Approach 1:
The patent applies local quality by restricting diversity to CDR regions while maintaining structural integrity in framework regions. The framework regions contain conserved structural motifs that prevent structural perturbations, while CDR regions are diversified for antigen binding. This spatial differentiation of diversity vs. stability resolves the contradiction.
Solution Approach 2:
The patent segments the antibody variable domain into CDR regions (for diversity) and framework regions (for structural stability). This segmentation allows independent optimization of each region: CDRs can be diversified for antigen binding while framework regions maintain conserved structural elements that prevent perturbations.
3Productivity
If antibody variable domains are produced in bacterial cells, then production efficiency is improved, but folding efficiency deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the amino acid sequence parameters of the antibody variable domain to be compatible with bacterial expression systems. Specific amino acid compositions and structural characteristics are optimized for bacterial folding capabilities, resolving the contradiction between production efficiency and folding efficiency.
Solution Approach 2:
The patent employs a simplified antibody variable domain design that is easier and cheaper to produce in bacterial cells, accepting that these domains may have limited functional lifespan or require careful handling. This approach prioritizes production efficiency and scalability over complex eukaryotic expression systems.
Data Source
AI summary
The invention provides polypeptides comprising a variant heavy chain variable framework domain (VFR). In some embodiments, the amino acids defining the VFR form a loop of an antigen binding pocket. In an embodiment, the polypeptide is a variable domain of a monobody and has a variant VFR. The polypeptide may optionally comprise one or more complementary determining regions (CDRs) of antibody variable domains. In an embodiment, the polypeptide is a variable domain of a monobody and has a variant VFR and one or more variant CDRs. Libraries of polypeptides that include a plurality of different antibody variable domains generated by creating diversity in a VFR, and optionally, one or more CDRs are provided and may be used as a source for identifying novel antigen binding polypeptides that can be used therapeutically or as reagents. The invention also provides fusion polypeptides, compositions, and methods for generating and using the polypeptides and libraries.