Synthetic DNA Sequences Optimizing Plant Protein Expression
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Solution Overview
Problem
Existing methods for enhancing protein expression in transgenic plants, such as those using Bacillus thuringiensis crystal protein insect toxins, are not effectively improved by reducing the number of polyadenylation signal sequences, contrary to previous teachings.
Innovation Solution
Development of synthetic DNA sequences optimized for maize and soybean genes, incorporating specific polyadenylation signal sequences while maintaining the same number of Class I sequences and reducing Class III sequences, to enhance protein expression in plants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of polyadenylation signal sequences is reduced according to previous teachings, then mRNA stability is expected to improve, but actual protein expression levels do not enhance
Solution Approach 1:
The patent changes the parameters of polyadenylation signal sequences by distinguishing between Class I (canonical) and Class III (non-canonical) sequences. Instead of simply reducing the total number of polyadenylation signals as previously taught, the invention specifically modifies the types and positions of these sequences - maintaining Class I sequences while adjusting Class III sequences to optimize both mRNA stability and protein expression levels in transgenic plants
Solution Approach 2:
The patent inverts the conventional approach by showing that reducing polyadenylation signal sequences is neither necessary nor sufficient for enhanced expression. Instead of following the traditional rule of reduction, the invention demonstrates that strategic placement and selection of specific polyadenylation signal classes can achieve better results, effectively reversing the conventional wisdom about what constitutes optimal gene design
2Productivity
If codon usage is optimized to match host plant species, then translation efficiency improves, but the complexity of synthetic DNA sequence design increases
Solution Approach 1:
The patent applies codon optimization by changing the nucleotide composition of the synthetic DNA sequence to match the codon usage preferences of the host plant species. This parameter change in the DNA sequence composition directly improves translation efficiency while the systematic approach to also optimizing polyadenylation signal sequences provides a comprehensive design framework that manages the overall complexity
3Stability of the object's composition
If G+C content is adjusted to match host plant species, then gene expression stability improves, but the manufacturing precision required for synthetic DNA increases
Solution Approach 1:
The patent adjusts the G+C content parameter of the synthetic DNA sequence to match the typical G+C levels found in coding sequences of the host plant species. This parameter optimization contributes to gene expression stability, and when combined with the systematic optimization of codon usage and polyadenylation signal sequences, creates a comprehensive approach that achieves stability while providing clear design guidelines for synthetic DNA manufacturing
Data Source
AI summary
The invention provides synthetic nucleic acid sequences encoding proteins of interest that are particularly adapted to express well in plants. The claimed synthetic sequences utilize plant-optimized codons roughly in the same frequency at which they are utilized, on average, in genes naturally occurring in the plant species. The invention further includes synthetic DNA sequence for herbicide tolerance, water and/or heat stress tolerance, healthy oil modifications and for transformation marker genes and selectable marker genes are used. DNA construct and transgenic plants containing the synthetic sequences are taught as are methods and compositions for using the plants in agriculture.