Site-Specific Incorporation of Sulfotyrosine Using an Expanded Genetic Code

Tyrosine sulfation is an important posttranslational modification found in bacteria and higher eukaryotes. However, the chemical synthesis or expression of homogenously sulfated proteins is particularly difficult, limiting our study and application of tyrosine-sulfated proteins. With the recent development of genomically recoded organisms and orthogonal translation components, we can often treat otherwise posttranslationally-modified amino acids as noncanonical amino acids (ncAAs) encoded by an expanded genetic code. Here, we describe methods for the co-translational incorporation of one or multiple sulfotyrosines into proteins using standard or genomically recoded Escherichia coli stains, thereby achieving the direct expression of site-specifically tyrosine sulfated proteins in vivo.