In vitro protein engineering using synthetic tRNA(Ala) with different anticodons

Area of Science:

• Molecular Biology
• Biochemistry
• Synthetic Biology

Background:

• Transfer RNAs (tRNAs) are essential molecules that mediate protein synthesis by translating genetic code.
• Modifying tRNA anticodons offers a potential avenue for expanding the proteinogenic amino acid repertoire and engineering novel proteins.
• Developing synthetic tRNAs for cell-free protein synthesis systems is crucial for advanced protein engineering applications.

Purpose of the Study:

• To investigate the functionality of synthetic tRNAs with altered anticodons in a coupled transcription/translation system.
• To assess the ability of these synthetic tRNAs to direct the synthesis of a specific protein, dihydrofolate reductase.
• To determine if the synthesized protein is full-length and enzymatically active.

Main Methods:

• Synthesized DNA sequences encoding modified tRNA(Ala/UGC) from Escherichia coli with altered anticodons.
• Cloned these synthetic tRNA genes into DNA plasmids for in vitro transcription using T7 RNA polymerase.
• Mutagenized the bacterial dihydrofolate reductase gene to create codons matching the synthetic tRNA anticodons.
• Utilized a coupled in vitro transcription/translation system from E. coli containing the synthetic tRNAs to produce dihydrofolate reductase.

Main Results:

• All four synthesized tRNA constructs, including those with anticodons for a stop codon, a rare arginine codon, and two novel stop codon suppressors, were functional.
• The synthetic tRNAs successfully directed the synthesis of full-length dihydrofolate reductase protein.
• The resulting dihydrofolate reductase protein was enzymatically active, demonstrating the biological relevance of the synthetic tRNAs.

Conclusions:

• Synthetic tRNAs with engineered anticodons are functionally active in a cell-free protein synthesis system.
• This approach enables the production of full-length, active proteins using non-canonical or modified codons.
• The successful application of synthetic tRNAs opens new possibilities for in vitro protein engineering and the creation of novel protein functionalities.