Custom codons come in threes, fours, and fives

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• The genetic code uses three-base codons to specify amino acids.
• Suppressor tRNAs can recognize non-canonical codons and alter protein synthesis.
• Understanding codon-anticodon interactions is crucial for deciphering the genetic code and protein synthesis.

Purpose of the Study:

• To investigate the viability of non-canonical codon-anticodon interactions.
• To determine the size constraints for functional codon-anticodon recognition.
• To explore the potential for frameshift suppression by non-standard codon-anticodon pairings.

Main Methods:

• Laboratory coselection experiments were performed.
• Reporter messages with randomized essential codons (2- to 6-base) were used.
• Suppressor tRNA(Ser) libraries with randomized anticodon loops were employed.

Main Results:

• Only four- and five-base codon-anticodon interactions were found to survive the selection process.
• These surviving suppressor tRNAs demonstrated the ability to perform +1 and -1 frameshift suppression.
• The identified suppressor tRNAs exhibited characteristics similar to serine tRNAs, including a potential bias towards serine anticodons.

Conclusions:

• The study indicates that functional codon-anticodon interactions can extend beyond the canonical three-base length.
• The findings suggest biological significance for four- and five-base codon recognition in frameshift suppression.
• Suppressor tRNAs capable of non-canonical interactions may possess inherent properties that facilitate their function and charging.