mRNA Engineering for Ribosomal Diversion and miRNA Evasion
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Solution Overview
Problem
Current methods for protein production, such as industrial production of protein drugs and DNA vaccines, face challenges due to sub-optimal protein synthesis rates and stability issues caused by upstream AUG codons and microRNA-mediated down-regulation, leading to inefficient protein yields and concentrations.
Innovation Solution
A method involving the modification of mRNA sequences by introducing a primary initiation codon upstream of the coding sequence and mutating secondary initiation codons within the coding sequence to reduce ribosomal diversion and evade microRNA binding sites, thereby enhancing protein expression efficiency without altering the amino acid sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If secondary initiation codons are present in the coding sequence, then ribosomes may initiate translation at multiple sites, but this leads to ribosomal diversion from the primary initiation codon and reduced full-length protein expression
Solution Approach 1:
The patent extracts and removes secondary initiation codons from the coding sequence through site-directed mutagenesis. By specifically mutating these codons to non-initiation sequences while preserving the amino acid sequence through synonymous mutations, the invention eliminates ribosomal diversion and enhances full-length protein expression efficiency.
2Reliability
If miRNA binding sites are present in the mRNA sequence, then gene regulation occurs, but this leads to reduced mRNA stability and decreased protein production
Solution Approach 1:
The patent identifies miRNA binding sites that negatively impact protein production and strategically mutates these sequences to eliminate miRNA binding while preserving the encoded amino acid sequence. This converts the harmful effect of miRNA-mediated down-regulation into a benefit by enhancing protein production efficiency without altering the functional protein product.
3Adaptability or versatility
If upstream AUG codons are present in the 5' leader, then translation initiation may occur at alternative sites, but this can have negative effects on protein synthesis by diverting ribosomes
Solution Approach 1:
The patent applies local quality control by specifically modifying the nucleotide context of upstream AUG codons in the 5' leader region. Through site-directed mutagenesis, the invention alters local sequence features to reduce the initiation competence of upstream codons while preserving the primary initiation codon's function, thereby directing ribosomes preferentially to the correct start site and enhancing overall protein synthesis efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases protein yields and concentrations, reducing costs and enabling the production of proteins that were previously difficult to produce, such as those required for phase 3 clinical trials and antigen generation.
Implementation Method 1
the initiator Methionine-tRNA, which is associated with the subunit, base-pairs to the initiation codon
Implementation Method 2
the 40S subunit moves from the site of recruitment to the initiation codon by scanning through the 5' leader in a 5' to 3' direction
Implementation Method 3
miRNAs can negatively impact protein levels by base-pairing to mRNAs and reducing mRNA stability, nascent peptide stability and translation efficiency
Data Source
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AI summary
Described herein are rules to modify natural mRNAs or to engineer synthetic mRNAs to increase their translation efficiencies. These rules describe modifications to mRNA coding and 3' UTR sequences intended to enhance protein synthesis by: 1) decreasing ribosomal diversion via AUG or non-canonical initiation codons in coding sequences, and/or 2) by evading miRNA-mediated down-regulation by eliminating one or more miRNA binding sites in coding sequences.