TrimerDimer: an oligonucleotide-based saturation mutagenesis approach that removes redundant and stop codons

Area of Science:

• Oligonucleotide synthesis
• Molecular biology
• Synthetic biology

Background:

• Orthogonal protecting groups like Fmoc and DMTr are crucial for oligonucleotide synthesis.
• Existing methods for saturation mutagenesis can be inefficient and generate unwanted codons.

Purpose of the Study:

• To develop a novel codon-based saturation mutagenesis approach called TrimerDimer.
• To efficiently assemble degenerate oligonucleotides by removing redundant and stop codons.

Main Methods:

• Utilized orthogonal protecting groups (Fmoc and DMTr) with specific chemical properties.
• Developed a stepwise phosphoramidite coupling strategy involving trinucleotides, dinucleotides, and monomers.
• Applied the TrimerDimer method to randomize codons in an engineered GFP protein.

Main Results:

• The TrimerDimer approach successfully generated 15 unique trinucleotides in one mutagenic cycle.
• This process yields all 20 natural amino acid codons.
• Demonstrated proof-of-principle by mutagenizing a GFP protein, yielding fluorescent mutants.

Conclusions:

• TrimerDimer is an effective strategy for codon-based saturation mutagenesis.
• The method streamlines the generation of diverse oligonucleotide libraries.
• Enables efficient creation of protein variants for functional studies.