Genetic-code evolution for protein synthesis with non-natural amino acids.

Area of Science:

• Synthetic biology
• Protein engineering
• Molecular biology

Background:

• The genetic code's expansion with non-natural amino acids can enhance protein function and structure.
• Current methods for incorporating non-natural amino acids are often limited or inefficient.

Purpose of the Study:

• To develop a method for efficient genetic encoding of non-natural amino acids in Escherichia coli.
• To enable the synthesis of proteins with non-natural amino acids at specific sites.
• To demonstrate the utility of this method for large-scale protein production and post-translational modification.

Main Methods:

• Rapid codon reassignment in Escherichia coli to alter the meaning of the UAG stop codon.
• Engineering of E. coli BL21 strain for large-scale recombinant protein production.
• Cell-free synthesis utilizing engineered E. coli cell extract.

Main Results:

• Successfully reassigned the UAG codon in E. coli to encode tyrosine and lysine derivatives.
• Enabled the synthesis of proteins containing non-natural amino acids alongside canonical ones.
• Demonstrated large-scale production of a histone H4 protein with specific lysine acetylation using cell-free systems.

Conclusions:

• Codon reassignment is a powerful strategy for genetically encoding non-natural amino acids.
• This approach significantly expands the toolkit for protein engineering and functional diversification.
• The engineered E. coli system is suitable for producing modified proteins for various applications, including epigenetics research.