CPMV Expression Enhancer for Large Insert Biocontainment
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Solution Overview
Problem
Current methods for producing foreign proteins in plants are time-consuming and labor-intensive, and plant virus-based expression systems face limitations in biocontainment and insert size, particularly with full-length viral vectors that restrict the size of sequences that can be inserted and raise concerns about viral movement.
Innovation Solution
The development of an expression enhancer system that includes a CPMV 5'UTR nucleotide sequence, a stuffer fragment encoding an incomplete M protein, and a plant kozak sequence, which enhances protein expression by allowing for the insertion of larger sequences and reducing the need for viral replication, while maintaining biocontainment through the use of disabled viral vectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If full-length viral vectors are used for protein expression, then high-level transient expression is achieved, but insert size is limited and biocontainment is compromised
Solution Approach 1:
The viral vector system is divided into two separate components: RNA-1 (containing replicase and protease genes) and RNA-2 (containing the expression enhancer and foreign protein gene). This segmentation allows RNA-2 to accommodate larger inserts without requiring full viral replication, thereby increasing insert size capacity while maintaining high-level expression through the expression enhancer.
Solution Approach 2:
The expression enhancer system extracts and utilizes specific functional elements (5'UTR, stuffer fragment, Kozak sequence) from the viral genome to create a standalone expression system. This extracted system can function with larger inserts by relying on co-inoculated RNA-1 for replication, thus resolving the contradiction between expression level and insert size.
2Productivity
If full-length viral vectors are used for protein expression, then high-level transient expression is achieved, but concerns about viral movement and biocontainment arise
Solution Approach 1:
By segmenting the viral vector into RNA-1 and RNA-2, the system reduces biocontainment risks. RNA-2 alone cannot replicate without RNA-1, and the disabled viral vectors with truncated M proteins cannot produce infectious particles. This segmentation maintains high-level expression while mitigating viral movement concerns.
Solution Approach 2:
The patent converts the potential harm of viral replication into a benefit by using a disabled viral vector system. The truncated M protein prevents viral assembly and spread, turning what would be a biocontainment risk into a safety feature. Meanwhile, the expression enhancer elements originally involved in viral replication are repurposed to drive high-level foreign protein expression without the harmful effects of full viral replication.
3Stability of the object's composition
If traditional transgenic plant lines are generated, then stable protein production is achieved, but the process is time-consuming and labor-intensive
Solution Approach 1:
The expression enhancer system is designed with pre-optimized elements (5'UTR, stuffer fragment, Kozak sequence) that are prepared in advance. When co-inoculated with RNA-1 into plants, this preliminary preparation enables rapid transient expression without the time-consuming steps of generating stable transgenic lines, thus reducing time and labor while maintaining production stability.
4Adaptability or versatility
If expression enhancer with stuffer fragment is used, then larger sequences can be inserted, but the complexity of the vector system increases
Solution Approach 1:
The expression enhancer system with stuffer fragment serves multiple functions: it maintains the reading frame for foreign protein expression, accommodates large inserts, provides Kozak sequences for efficient translation initiation, and works with the simplified two-component RNA-1/RNA-2 system. This multi-functionality increases versatility without proportionally increasing complexity.
Data Source
AI summary
An expression enhancer comprising, in series, a CPMV 5′UTR nucleotide sequence comprising nucleotides 1-160 of SEQ ID NO:1, or comprising a nucleotide sequence comprising from about with 80% to 100% sequence similarity with SEQ ID NO:1, and a stuffer fragment is provided. The stuffer fragment comprises a nucleotide sequence encoding an incomplete M protein and one or more kozak sequence active in a plant. Plants and plant matter comprising the expression enhancer and methods using the expression enhancer are also described.