Heliothis Transposase Mutations for Stable Eukaryotic DNA Integration
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Solution Overview
Problem
Existing piggyBac-like transposases are difficult to identify and implement effectively for stable integration and expression of heterologous DNA in eukaryotic genomes due to host inactivation and low transposition frequencies, necessitating the development of new transposon-transposase systems with improved activity and specificity.
Innovation Solution
Development of novel piggyBac-like transposon-transposase systems derived from Heliothis virescens, Agrotis ipsilon, and Helicoverpa armigera, featuring specific transposase mutations and configurations to enhance excision and transposition activities, allowing stable integration and expression of heterologous DNA in eukaryotic cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing piggyBac-like transposases are used for integration of heterologous DNA, then transposition occurs, but the activity is low and transposition frequency is low due to host inactivation
Solution Approach 1:
The patent applies parameter changes by mutating specific amino acid residues in the transposase sequence (e.g., positions 41, 43, 81, 83, 85, 125, 126, 131, 136, 140, 149, 151, 152, 153, 155, 162, 169, 212, 238, 239, 241, 264, 268, 280, 297, 299, 300, 305, 312, 316, 322, 357, 360, 396, 397, 421, 430, 447, 449, 450, 476, 485, 492, 495, 507, 512, 585, 589, 595, 603) to enhance transposase activity and transposition frequency while overcoming host inactivation mechanisms
Solution Approach 2:
The patent creates copies of the transposase gene with modified sequences that are more resistant to host inactivation. By introducing synonymous mutations and amino acid substitutions, the patent generates improved transposase variants that maintain function while evading host suppression mechanisms
2Adaptability or versatility
If multiple different polynucleotides are integrated into the genome sequentially, then genomic engineering is achieved, but transposition of previously integrated transposons may occur changing expression properties
Solution Approach 1:
The patent segments the transposase function into multiple specialized variants, each recognizing specific transposon types. This segmentation prevents cross-reactivity where one transposase might inadvertently transpose previously integrated transposons, thereby maintaining expression stability while enabling sequential genomic engineering
Solution Approach 2:
The patent applies local quality by creating transposases with specialized recognition specificities for different transposon ends. Each transposase variant is locally optimized to recognize and transpose only its corresponding transposon type, preventing unwanted transposition events that would alter expression properties of previously integrated genes
3Productivity
If transposases with high activity are developed, then transposition efficiency increases, but specificity for recognizing only corresponding transposons must be maintained
Solution Approach 1:
The patent applies asymmetry by creating transposase variants with asymmetric amino acid substitutions that enhance binding affinity and catalytic efficiency for their specific target transposons. The asymmetric mutations in regions such as the transposon recognition domain increase specificity while the catalytic domain mutations enhance overall transposition efficiency
Data Source
Figure 1
AI summary
The present invention provides polynucleotide vectors for high expression of heterologous genes. Some vectors further comprise novel transposons and transposases that further improve expression. Further disclosed are vectors that can be used in a gene transfer system for stably introducing nucleic acids into the DNA of a cell. The gene transfer systems can be used in methods, for example, gene expression, bioprocessing, gene therapy, insertional mutagenesis, or gene discovery.