Site-Specific Incorporation of 7-Fluoro-L-tryptophan into Proteins by Genetic Encoding to Monitor Ligand Binding by 19F NMR Spectroscopy

A mutant aminoacyl-tRNA synthetase identified by a library selection system affords site-specific incorporation of 7-fluoro-L-tryptophan in response to an amber stop codon. The enzyme allows the production of proteins with a single hydrogen atom replaced by a fluorine atom as a sensitive nuclear magnetic resonance (NMR) probe. The substitution of a single hydrogen atom by another element that is as closely similar in size and hydrophobicity as possible minimizes possible perturbations in the structure, stability, and solubility of the protein. The fluorine atom enables site-selective monitoring of the protein response to ligand binding by F-19 NMR spectroscopy, as demonstrated with the Zika virus NS2B-NS3 protease.

Automated summary

A mutant aminoacyl-tRNA synthetase has been discovered through a library selection system that allows for the site-specific incorporation of 7-fluoro-L-tryptophan in response to an amber stop codon. This enzyme enables the production of proteins with a single hydrogen atom replaced by a fluorine atom, serving as a sensitive nuclear magnetic resonance (NMR) probe. The substitution of a single hydrogen atom with a similar-sized and hydrophobicity element minimizes potential disruptions to the protein's structure, stability, and solubility. The fluorine atom facilitates the site-selective monitoring of protein response to ligand binding using F-19 NMR spectroscopy, as demonstrated with the Zika virus NS2B-NS3 protease.