Degenerate Codon Primers for Targeted Protein Mutagenesis
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Solution Overview
Problem
Current methods of mutagenesis often result in large, unmanageable libraries with random mutations, including those outside the area of interest, requiring extensive screening and backmutation to identify productive mutations, especially when targeting specific amino acid positions in proteins like antibodies or enzymes.
Innovation Solution
The use of primers with 2 to 12 fold degenerate codons that exclude cysteine and methionine, allowing for targeted mutagenesis by generating variant nucleic acid sequences with equal representation of non-redundant amino acid changes at specific positions, facilitating the creation of smaller, focused libraries of modified proteins with desired biological activities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If saturation mutagenesis uses primers with degenerate codons (NNN, NNK, or NNS) that code for all possible amino acid substitutions, then comprehensive variant coverage is achieved, but library size becomes unmanageably large requiring multiple large libraries and extensive screening
Solution Approach 1:
The patent applies local quality by using different degeneracy levels (2-fold to 12-fold) at different codon positions within the same primer. This allows certain positions to explore more amino acid variants while other positions maintain lower degeneracy, creating a balanced library that covers diverse variants without requiring exhaustive screening of all possible combinations.
Solution Approach 2:
The patent uses partial action by implementing non-uniform degeneracy distribution where not all codon positions are maximally degenerate. Instead of uniform NNN (64-fold) degeneracy throughout, specific positions use reduced degeneracy (2-fold, 4-fold, 6-fold, 8-fold, or 12-fold), thereby generating a manageable library size that still captures the most important variants for the research objective.
2Ease of manufacture
If error prone PCR is used to introduce random mutations, then mutation generation is simplified, but mutations occur at random positions including outside the area of interest requiring backmutation to identify productive mutations
Solution Approach 1:
The patent applies preliminary action by pre-designing primers with degenerate codons positioned at specific locations within the gene sequence. This allows mutations to be introduced only at predetermined positions of interest before the amplification process begins, eliminating the need for subsequent backmutation steps required by error-prone PCR methods.
Solution Approach 2:
The patent uses degenerate codons as intermediaries that bridge the gap between simple random mutagenesis and precise site-directed mutagenesis. These codons serve as mediators that introduce controlled variability at specific positions during PCR amplification, combining the ease of PCR-based methods with the precision of targeted mutation introduction.
3Adaptability or versatility
If degenerate codons are used to explore all possible amino acid substitutions, then complete amino acid representation is achieved, but certain amino acids become overrepresented (e.g., Arg, Leu, and Ser) due to genetic code degeneracy
Solution Approach 1:
The patent applies parameter changes by modifying the degeneracy parameter of codons at different positions. Instead of using uniform high degeneracy (NNN = 64-fold) that causes amino acid overrepresentation, the patent varies degeneracy levels (2-fold, 4-fold, 6-fold, 8-fold, or 12-fold) to control the frequency distribution of encoded amino acids, thereby achieving more uniform representation.
Solution Approach 2:
The patent implements asymmetry by using non-uniform degeneracy distribution across different codon positions within primers. This asymmetric approach deliberately creates different levels of variability at different positions, which compensates for the inherent symmetry and overrepresentation problems of standard degenerate codons like NNN, leading to more balanced amino acid frequency distribution in the generated library.
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 enables the efficient generation of modified proteins with improved biological properties by ensuring equal representation of amino acid changes at specific positions, reducing the need for extensive screening and enhancing the identification of productive mutations.
Implementation Method 1
subjecting the parent nucleic acid sequence to replication or polymerase based amplification using the obtained primers, wherein replication or amplification of the parent nucleic acid sequence with the primers generates variant nucleic acid sequences
Data Source
AI summary
The present disclosure relates to methods and materials for mutagenesis, including for the generation of novel or improved proteins and libraries or arrays of mutant proteins or nucleic acids encoding such mutant proteins.