Modubody Monospecific Polypeptide for Stable Bacterial Expression
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Solution Overview
Problem
Current methods for producing antibodies and antibody fragments face challenges such as low yield, instability, and high production costs, particularly in bacterial expression systems, and existing calibrators for immunodiagnosis are difficult to produce in large quantities with consistent binding characteristics.
Innovation Solution
Development of monovalent fusion polypeptides, referred to as 'modubodies,' which consist of domains from the heavy chain variable region, light chain variable region, and heavy chain constant region of antibodies linked via peptide linkers, allowing for easy production in bacterial systems and providing stability and specificity for diagnostic and therapeutic applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional antibody fragments (Fab, Fv) are produced in bacterial expression systems, then antigen-binding specificity is achieved, but production yield is low and the process is complex
Solution Approach 1:
The invention segments the antibody molecule into functional domains (VH, VL, CH1, CH2, CH3) and reassembles them in a simplified single-chain configuration. This segmentation allows each domain to be optimized independently while achieving the desired antigen-binding specificity through the VH-VL interface, while the simplified structure enables high production yield in bacterial systems.
Solution Approach 2:
The invention merges the variable domains (VH, VL) with constant domains (CH1, CH2, CH3) into a single continuous polypeptide chain connected by peptide linkers. This merging creates a stable, monomeric structure that maintains antigen-binding specificity while eliminating the need for complex multi-subunit assembly, thereby achieving high production yield in bacterial expression systems.
2Ease of manufacture
If single-chain Fv fragments (scFv) are produced in bacterial expression systems, then production simplicity is improved, but folding efficiency and stability are inadequate
Solution Approach 1:
The invention applies local quality by incorporating stable constant domains (CH1, CH2, CH3) with well-defined three-dimensional structures into the scFv framework. These constant domains provide structural anchors that guide the folding of the entire molecule and enhance its stability, while the variable domains (VH, VL) maintain their antigen-binding function. This localized structural reinforcement resolves the folding efficiency and stability issues of conventional scFv.
Solution Approach 2:
The invention creates a composite protein structure combining variable domains (VH, VL) with constant domains (CH1, CH2, CH3) through peptide linkers. This composite construction leverages the stability of the constant domains to support the variable domains, resulting in a molecule that is both easy to produce in bacterial systems and possesses enhanced folding efficiency and structural stability.
3Reliability
If minibody molecules are expressed in E. coli, then antigen-binding capability is achieved, but expression rate is low and proteolytic degradation occurs
Solution Approach 1:
The invention extracts the hinge region and disulphide bridge-forming elements from the minibody structure, retaining only the essential variable domains (VH, VL) and stable constant domains (CH1, CH2, CH3) connected by peptide linkers. This extraction eliminates the proteolytically sensitive hinge region while preserving antigen-binding capability, thereby achieving high expression rates in E. coli without proteolytic degradation.
4Adaptability or versatility
If polyclonal antibodies are used for diagnostic assays, then binding diversity is achieved, but production cost and complexity increase
Solution Approach 1:
The invention creates universal modubody platforms that can be designed to bind multiple different antigens by simply changing the VH and VL domain sequences while maintaining the same basic structural framework (VH-L-VH-L-CH1-CH2-CH3). This multi-functionality allows a single production system to generate multiple specific reagents, achieving binding diversity without the complexity and cost of producing multiple separate polyclonal antibody preparations.
Data Source
AI summary
The present invention relates to a novel antigen-binding protein construct or “modubody”, which contains at least three functional single domain modules of an antibody. The modubodies contain a domain from the heavy chain variable region of an antibody (VH), a domain from the light chain variable region of an antibody (VL) and bind monospecifically to an antigen. The modubodies further contain a domain from the constant region of antibodies. The modubodies can be used for diagnostic or therapeutic purposes.