Evaluation and biosynthetic incorporation of chlorotyrosine into recombinant proteins

Recently, non-canonical amino acids (NCAA) incorporation was developed to enhance the functional properties of proteins. Incorporation of NCAA containing chlorine atom is conceptually an attractive approach to prepare pharmacologically active substances, which is a difficult task since chlorine is bulky atom. In this study, we evaluated the efficiency and extent of in vivo incorporation of tyrosine analogue 3-chlorotyrosine [(3-Cl)Tyr] into the recombinant proteins GFP and GFPHS (highly stable GFP). The incorporation of (3-Cl)Tyr into GFP leads to dramatic reduction in the expression level of protein. On the other hand, the incorporation of (3-Cl)Tyr into GFPHS was expressed well as a soluble form. In addition we used bioinformatics tools for the analysis to explore the possible constraints in micro-environment of each natural amino acid residue to be replaced with chlorine atom accommodation into GFPHS. In conclusion, our approaches are reliable and straightforward way to enhance the translation of chlorinated amino acids into proteins.