Expanding the genetic code of C. elegans

Abstract

Expanding the genetic code of an organism allows for the co-translational incorporation of amino acids beyond the 20 canonical ones found in nature. These additional non-canonical amino acids (ncAAs) can impart unique functionalities onto proteins, providing novel approaches to study and manipulate biological processes. For example, the site-specific labelling of proteins can be achieved by introducing ncAAs that take part in bioorthogonal reactions, or protein activity can be photocaged by introducing photocaged amino acids.

Genetic code expansion is achieved by aminoacyl-tRNA synthetase (aaRS)/tRNA pairs that are orthogonal to the organism’s own. The orthogonal aaRS specifically aminoacylates the orthogonal tRNA with a specific ncAA that is co-translationally incorporated into the protein of interest in response to a specific blank codon recognised by the tRNA anticodon. In C. elegans only a single aaRS/tRNA pair has been applied thus far, limiting genetic code expansion to a single ncAA at a time, and therefore limiting its applications. Here I describe, for the first time in a multicellular organism, mutually orthogonal aaRS/tRNA pairs and new blank codons that make it possible to concurrently incorporate different ncAAs into the same or different proteins in the same cell.