Plant Chimeric Binding Polypeptides for Expression in Transgenic Plants
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Solution Overview
Problem
Expressing immunoglobulins in transgenic plants is challenging due to improper folding, large size issues, and consumer acceptance concerns, limiting their use as protein pesticides or targeting molecules.
Innovation Solution
Generating diverse libraries of nucleic acids encoding plant chimeric binding polypeptides with varied binding domains derived from plant protein sequences, which are structurally robust and can be expressed in plants, overcoming the limitations of immunoglobulin expression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If immunoglobulins are expressed in transgenic plants, then binding diversity and affinity are improved, but proper folding and structural stability deteriorate due to disulfide bond formation requirements
Solution Approach 1:
The patent extracts only the essential binding function from immunoglobulins by using smaller binding domains (Fab fragments, scFv, or nanobodies) instead of full-length antibodies. This extraction removes the problematic large structure while retaining the binding capability, resolving the contradiction between binding affinity and proper folding in plant systems
Solution Approach 2:
The patent employs small, simple binding domain structures that are easier and more reliable to express in plant systems. These simplified structures act as 'disposable' solutions that don't require the complex disulfide bond networks of full immunoglobulins, making them more suitable for plant-based expression while maintaining binding function
2Reliability
If full-size immunoglobulins are used, then binding specificity is improved, but uptake by plant pests deteriorates due to large molecular size
Solution Approach 1:
The patent extracts only the essential antigen-binding fragment (Fab or smaller) from the full immunoglobulin structure. This extraction reduces molecular size to facilitate pest uptake while preserving the hypervariable regions that provide binding specificity, thus resolving the contradiction between specificity and ease of uptake
3Adaptability or versatility
If immunoglobulins are expressed in edible plants, then binding functionality is improved, but consumer acceptance deteriorates due to mammalian protein concerns
Solution Approach 1:
The patent extracts the binding function from mammalian immunoglobulins and implements it using plant-compatible protein structures. This extraction eliminates the need for mammalian protein expression in edible plants while maintaining binding functionality, resolving the contradiction between versatility and consumer acceptance
Solution Approach 2:
The patent changes the structural parameters of the binding protein from mammalian immunoglobulin architecture to plant-compatible architectures (such as plant-derived scaffolds or simplified binding domains). This parameter change allows the protein to function in edible plants without raising consumer concerns about mammalian proteins
4Adaptability or versatility
If diverse immunoglobulin libraries are constructed, then binding diversity is improved, but expression reliability in plants deteriorates due to structural complexity
Solution Approach 1:
The patent extracts the binding diversity function from complex immunoglobulin libraries and implements it using simpler, plant-compatible binding domain libraries. This extraction maintains the ability to generate diverse binding specificities while using structurally simpler units that express more reliably in plant systems
Solution Approach 2:
The patent changes the structural parameters of the library members from complex immunoglobulin architectures to simplified binding domains with plant-compatible folding requirements. This parameter change enables diverse binding functions to be expressed reliably in plants by eliminating disulfide bond dependencies
Data Source
AI summary
Libraries of nucleic acids encoding chimeric binding polypeptides based on plant scaffold polypeptide sequences. Also described are methods for generating the libraries.