Hyperactive Transposases for Efficient Genome Integration
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Solution Overview
Problem
Current methods for integrating heterologous DNA into target cell genomes are inefficient, with limitations in expression levels, size of DNA sequences that can be integrated, and specificity of genomic loci, necessitating the development of more active transposases and transposons for improved gene expression.
Innovation Solution
The introduction of novel piggyBac-like transposon-transposase systems derived from Bombyx mori and Xenopus tropicalis, which include hyperactive and integration-deficient transposase variants, to facilitate efficient integration and expression of heterologous genes by using specific transposon ends and inverted terminal repeats recognized by these transposases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional integration methods are used, then integration can occur, but the efficiency is low and expression levels are limited
Solution Approach 1:
The patent modifies transposase enzymes by introducing amino acid substitutions to create hyperactive variants with enhanced catalytic activity. Specific mutations in the transposase active site increase the frequency of transposition events, thereby improving both integration efficiency and subsequent expression levels from integrated DNA.
Solution Approach 2:
The patent constructs synthetic transposons by combining heterologous DNA sequences with transposon terminal repeats from piggyBac or related elements. This composite structure allows the heterologous DNA to be efficiently transposed and integrated into the host genome, overcoming limitations of conventional integration methods.
2Length of moving object
If transposon size is increased to integrate larger DNA sequences, then more genes can be inserted, but transposition efficiency decreases
Solution Approach 1:
The patent divides large DNA sequences into smaller modular units that can be individually transposed. By using multiple transposon vectors that can be sequentially introduced, large genomic modifications can be achieved through stepwise integration of smaller DNA fragments, maintaining high transposition efficiency at each step.
Solution Approach 2:
The patent uses hyperactive transposases that exhibit excessive catalytic activity to ensure complete transposition even of larger DNA sequences. The enhanced enzyme activity compensates for the reduced transposition frequency that would normally occur with larger substrates.
3Ease of repair
If integration-deficient transposases are used, then transposon excision is improved, but integration capability is lost
Solution Approach 1:
The patent employs a two-stage transposition strategy where a wild-type transposase performs initial integration, followed by expression of an integration-deficient transposase variant that can excise the transposon but cannot re-integrate it. This dynamic switching of transposase activity enables precise control over transposon retention or removal based on experimental requirements.
Data Source
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.