A Genetically Encoded Redox-Active Nicotinamide Amino Acid.

Nicotinamide-containing cofactors play an essential role in many enzymes that catalyze two-electron redox reactions. However, it is difficult to engineer nicotinamide binding sites into proteins due to the extended nature of the cofactor-protein interface and the precise orientation of the nicotinamide moiety required for efficient electron transfer to or from the substrate. To address these challenges, we genetically encoded a noncanonical amino acid (ncAA) bearing a nicotinamide side chain in bacteria.

Recent advances in the expanding genetic code.

For over a billion years, the central dogma of biology has been limited largely to 20 canonical amino acids with relatively simple functionalities. The ability to rationally add new building blocks to the genetic code has enabled the site-specific incorporation of hundreds of noncanonical amino acids (ncAAs) with novel properties into proteins in living organisms. Recent technological advances have enabled high level mammalian expression of proteins containing ncAAs, the use of unique codons to direct ncAA incorporation, extension of this methodology to a range of eukaryotic organisms, and the ability to encode building blocks beyond α-amino acids.