Genetic Encoding of Arylazopyrazole Phenylalanine for Optical Control of Translation.

An arylazopyrazole was explored for its use as an enhanced photoswitchable amino acid in genetic code expansion. This new unnatural amino acid was successfully incorporated into proteins in both bacterial and mammalian cells. While photocontrol of translation required pulsed irradiations, complete selectivity for the trans -configuration by the pyrrolysyl tRNA synthetase was observed, demonstrating expression of a gene of interest selectively controlled via light exposure.