1. Biochemistry and Chemical Biology
Download icon

Genetic Code: Expanding codon size

  1. Tarana Siddika
  2. Ilka U Heinemann
  3. Patrick O’Donoghue  Is a corresponding author
  1. Department of Biochemistry, The University of Western Ontario, Canada
  2. Department of Biochemistry, Department of Chemistry, The University of Western Ontario, Canada
Insight
Cite this article as: eLife 2022;11:e78869 doi: 10.7554/eLife.78869
1 figure

Figures

Evolving tRNAs to efficiently read quadruplet codons.

The schematic illustrates the approach used by DeBenedictis et al. to evolve triplet-decoding tRNAs (left) into tRNAs with expanded anticodon loops (red dots) to decode quadruplet codons consisting of four nucleotide bases (N; middle), and ultimately into efficient quadruplet codon decoders (right). To test the efficiency of four-base translation, DeBenedictis et al. created reporter genes (such as luciferase) with a single base insertion (also referred to as +1 frameshift). The ability of a particular tRNA variant to read that +1-frameshift mutation as a four-base codon can be measured as a function of how much full length and active reporter protein (e.g., luciferase) is made in cells. DeBenedictis et al. then recorded the translation efficiency of tRNAs with simple mutations to expand the anticodon loop (middle, red dots). Next, tRNAs were evolved through various mutations into more effective quadruplet-decoding tRNAs (qtRNAs, purple dots, right). The work represents an important step towards engineering a quadruplet genetic code with 256 codons.

Image credit: Tarana Siddika, Ilka U. Heinemann, Patrick O’Donoghue (CC BY 4.0).

Download links

A two-part list of links to download the article, or parts of the article, in various formats.

Downloads (link to download the article as PDF)

Download citations (links to download the citations from this article in formats compatible with various reference manager tools)

Open citations (links to open the citations from this article in various online reference manager services)