Seed-Specific Heme Protein Expression Cassettes for Transgenic Plants
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Solution Overview
Problem
Existing technologies have not achieved high expression levels (e.g., >5% total soluble protein) of heme proteins in transgenic plant seeds, which are crucial for producing meat-like color, flavor, and nutritional value in plant-based protein products.
Innovation Solution
Utilizing a combination of seed-specific promoters and transcription/translation enhancers, such as the beta-conglycinin alpha subunit (7S) promoter from soybean, beta-phaseolin promoter from common bean, and translational enhancers like 5' UTR from Tobacco Etch Virus (TEV), along with appropriate terminators, to operatively link exogenous nucleic acids encoding heme proteins, resulting in expression levels of at least 5%, 8%, or 10% total soluble protein in transgenic plant seeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional promoters and expression cassettes are used in transgenic plants, then the production process is simple, but the expression level of heme proteins remains low (below 5% total soluble protein)
Solution Approach 1:
The patent combines multiple regulatory elements (seed-specific promoter, enhancer, and terminator) into a single expression cassette to achieve high expression levels. The expression cassette integrates the 7S promoter, Phaseolin promoter, TEV enhancer, and Arc5 terminator into one functional unit that drives high-level heme protein expression in plant seeds.
Solution Approach 2:
The patent modifies the expression cassette by changing key parameters such as using seed-specific promoters (7S, Phaseolin) instead of constitutive promoters, adding enhancer elements (TEV, Arc5), and optimizing the promoter-terminator distance. These parameter changes result in expression levels increasing from below 5% to over 10% total soluble protein.
2Quantity of substance
If high expression cassettes with multiple regulatory elements are used, then the expression level of heme proteins increases (>10% total soluble protein), but the complexity of the expression system increases
Solution Approach 1:
The expression cassette is segmented into distinct functional modules: promoter (7S or Phaseolin), enhancer (TEV or Arc5), and terminator. This segmentation allows each element to be independently optimized and selected, making the construction process more manageable despite the increased complexity.
Solution Approach 2:
The patent creates universal expression cassettes that can be applied across different plant species and heme protein types. The modular design with standardized promoters and enhancers allows the same cassette structure to drive expression of various heme proteins (hemoglobin, myoglobin, cytochromes) in different plant seeds, simplifying future applications.
3Ease of manufacture
If plant-based meat alternatives are produced without high expression of heme proteins, then the production process is straightforward, but the product lacks meat-like color, flavor, and nutritional value
Solution Approach 1:
The heme protein is expressed at high levels in the plant seed before the seed is used in food production. This preliminary action of accumulating heme protein in the seed during plant growth allows the final food product to contain high concentrations of heme protein without requiring complex post-production processing or supplementation steps.
Data Source
AI summary
The present disclosure provides methods of producing heme proteins in transgenic plants, plant tissues, or plant cells, as well as describing the expression of these heme proteins in seeds. Also, the present disclosure provides transgenic plants expressing the heme proteins, myoglobin and hemoglobin, by introducing and integrating the recombinant DNA constructs into the host genetic material of the subject plants. The specific combination of regulatory elements disclosed herein allows for high heme protein expression level in seeds.