Minimal Recombinant PolyA Sequences for Stable Multigene Expression
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Solution Overview
Problem
Existing recombinant protein expression systems face challenges in achieving stable, high-level expression of multiple genes from a single vector due to sequence variability and recombination risks, particularly with polyadenylation signal sequences, which affect expression levels and vector stability.
Innovation Solution
Development of a set of rationally designed recombinant polyadenylation signal sequences based on the minimal core sequence of the RbG polyadenylation signal, optimized for multigene expression vectors to reduce recombination risks and enhance expression levels, with sequence lengths under 100 nucleotides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If longer polyadenylation signal sequences are used, then expression levels are improved, but vector size increases reducing transfection efficiency
Solution Approach 1:
The patent extracts only the essential functional elements required for polyadenylation activity from the full-length polyA sequences. By identifying and retaining only the critical nucleotides needed for transcription termination and polyA tail addition, the invention creates truncated sequences that maintain high expression levels while significantly reducing vector size, thus resolving the contradiction between expression efficiency and transfection efficiency.
Solution Approach 2:
The invention replaces traditional long polyA sequences with short, synthetic minimal polyA sequences. These shortened sequences serve the same functional purpose but with reduced length, analogous to using disposable short-living objects that are simpler and more efficient. The minimal sequences are designed to be sufficient for their function without the bloat of unnecessary nucleotides, improving transfection while maintaining expression.
2Reliability
If identical polyadenylation signal sequences are replicated for multiple expression units, then expression consistency is improved, but recombination risk increases
Solution Approach 1:
The patent applies asymmetry by designing multiple polyA sequences that are functionally equivalent but sequence-diverse. Instead of replicating identical sequences across multiple expression units, the invention creates asymmetric variants with different nucleotide compositions that all perform the same polyadenylation function. This prevents homologous recombination between repeated elements while maintaining consistent expression levels across all transgenes.
Solution Approach 2:
The invention implements local quality by allowing each polyA sequence to have unique local characteristics (specific nucleotide variations) while maintaining the same overall function. Each minimal polyA sequence is locally optimized with slight variations in composition, ensuring that no two identical sequences exist in the same vector, thereby eliminating recombination risks while preserving expression consistency through functional equivalence.
3Reliability
If polyadenylation signal sequences with additional functional elements are used, then transcription termination efficiency is improved, but sequence length and complexity increase
Solution Approach 1:
The patent extracts only the absolutely essential functional elements required for transcription termination and polyadenylation from complex polyA sequences. By removing non-essential upstream and downstream functional elements that do not contribute significantly to core termination efficiency, the invention creates minimal sequences that achieve sufficient termination reliability without the complexity of additional regulatory elements.
Data Source
AI summary
The present invention relates to improved recombinant polyadenylation signal sequences and use thereof.