Maize Intron Terminator Expression Cassette Design
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Solution Overview
Problem
Current plant expression cassettes often fail to produce adequate trait proteins due to limitations in spatial and temporal transcription control, with introns and terminators playing a significant but understudied role in nucleic acid expression, particularly in plants, where only a few introns and terminators have been evaluated for their enhancing effects.
Innovation Solution
The use of specific heterologous introns and terminators, such as SEQUENCE ID NO. 1 (iZm10430-02), SEQUENCE ID NO. 2 (iZm10430-01), SEQUENCE ID NO. 3 (iZm008975-01), SEQUENCE ID NO. 4 (iZm005854-01), SEQUENCE ID NO. 5 (iZm010719-01), and SEQUENCE ID NO. 6 (iZm007840-01) for introns, and SEQUENCE ID NO. 7 (tZmHSP70-01), SEQUENCE ID NO. 8 (tZmUbi158-01), SEQUENCE ID NO. 9 (tZmUbi1-01), SEQUENCE ID NO. 10 (tZmUbi361-01) for terminators, within expression cassettes to enhance the expression of nucleic acid molecules of interest in plants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional plant expression cassettes are used with standard promoters and terminators, then spatial and temporal transcription control is achieved, but protein production levels are inadequate
Solution Approach 1:
The patent applies parameter changes by substituting specific intron sequences (from maize genes such as shrunken-1, opaque-2, and waxy) and terminator sequences into the expression cassette to optimize transcription and translation efficiency. These sequence substitutions change the biochemical parameters of gene expression, enabling protein production levels to increase up to 10-fold while preserving spatial and temporal control through promoter selection.
2Productivity
If introns are added to enhance expression, then protein production increases up to 10-fold, but expression cassette complexity increases
Solution Approach 1:
The patent uses introns as intermediary elements that mediate between the promoter and the coding sequence to enhance expression. The introns act as facilitators that improve transcription efficiency and mRNA processing without disrupting the overall cassette structure. By selecting specific intron sequences from well-characterized maize genes, the patent achieves high protein production while maintaining manageable cassette design through the use of these proven intermediary elements.
3Productivity
If heterologous introns and terminators are used, then nucleic acid expression is enhanced, but knowledge about mechanism and optimal selection is limited
Solution Approach 1:
The patent applies preliminary action by pre-selecting and characterizing specific intron and terminator sequences from maize genes before using them in expression cassettes. The introns from genes like shrunken-1, opaque-2, and waxy have been preliminarily evaluated for their splicing efficiency and expression-enhancing properties. This preliminary characterization provides a foundation for predictable cassette design, reducing the information loss about mechanism by establishing known-effective sequence elements that can be reliably used across different expression contexts.
Data Source
AI summary
In one aspect, the present invention provides an expression cassette comprising a promoter operably linked to a nucleic acid molecule of interest, which is operably linked to a terminator, further comprising a heterologous intron that enhances expression of the nucleic acid molecule of interest, wherein the heterologous intron is selected from the group comprised of SEQUENCE ID NO. 1 (iZm10430-02), SEQUENCE ID NO. 2 (iZm10430-01) SEQUENCE ID NO. 3 (iZm008975-01), SEQUENCE ID NO. 4 (iZm005854-01), SEQUENCE ID NO. 5 (iZm010719-01), and SEQUENCE ID NO. 6 (iZm007840-01). In another aspect, the present invention provides an expression cassette comprising a promoter operably linked to a nucleic acid molecule of interest, which is operably linked to a heterologous terminator that enhances expression of the nucleic acid molecule of interest, wherein the heterologous terminator is selected from the group of SEQUENCE ID NO. 7 (tZmHSP70-01), SEQUENCE ID NO. 8 (tZmUbi158-01), SEQUENCE ID NO. 9 (tZmUbi1-01), SEQUENCE ID NO. 10 (tZmUbi361-01).