earticle

영어

Genetic code engineering is a recent developing method that became an indispensable quest to design and manipulate target proteins with novel functionality embedded within unnatural amino acid (UAA).
Frequently, two experimental approaches were used for reassignment of sense (residue specific incorporation) and non sense codon (site specific incorporation) with UAA through in vivo expression of recombinant proteins. Even though, both of these methods successfully alter the protein functionality, the limitations of above methods is that they allow only incorporation of a single unnatural amino acid into the recombinant protein. Here we developed a promising alternative approach through coupling of both sense and suppression method in single protein. To explore the possibility for MUAA incorporation, we selected green fluorescent protein (GFP) as a model protein that contain five methionine codons and these codons will be reassigned with methionine surrogate l-homopropargylglycine (Hpg) whose functionality can be chemoselectively modified with specific alkyne bearing reagent by means of a copper mediated azide-alkyne cycloaddition (click chemistry). Simultaneously, tyrosine analogue L-3, 4-dihydroxyphenylalanine (L-DOPA) will be site specifically incorporated into chromophore tyrosine (Y66) by an evolved Methanococcus jannaschii tRNA/synthetase pairs (mutant TyrRS). This is the first study to demonstrate in vivo incorporation of two unnatural amino acids into a recombinant protein through combination of two different methodologies. This combination will offer extraordinary opportunity for protein engineers to create protein with novel functionality which expand the proteome of the cell. This approach will drive us toward a post proteomics era as well as it will also open a new door for synthetic biologist to generate multi characteristic proteins.