Although triplet codons are the predominant form of genetic code in nature, programmed frameshift, e.g., +1 frameshift (quadruplet codon decoding), is a natural process. Recent developments in genetic code engineering also demonstrated that quadruplet codon could be used to encode unnatural amino acids (unAAs) under experimental conditions. In order to precisely translate genetic information, protein biosynthetic machinery must be able to decide when to use quadruplet codon decoding instead of standard triplet codon decoding through highly specific molecular interactions among its components. Transfer RNA (tRNA), the molecule decodes the genetic message, plays important roles in the reading frame maintenance process. Here we report the engineering and application of quadruplet decoding tRNAs that bear extended anticodon loops (8-base instead of normal 7-base loop) with apparent quadruplet anticodons. We found that the quadruplet decoding efficiency can be greatly promoted by modifying the sequence/structure of tRNA. We also demonstrated that the evolved tRNA were able to decode a quadruplet codon in both bacteria and mammalian cells. Our ability to evolve a large collection of quadruplet codon decoding tRNAs will likely lead to better mechanistic understanding of the quadruplet codon decoding process as well as provide new blank codons for cellular genetic code expansion.

Quadruplet codon decoding

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.