Genetically encoded initiator for polymer growth from proteins

Area of Science:

• Bioconjugation Chemistry
• Protein Engineering
• Polymer Science

Background:

• Protein-polymer bioconjugates are crucial for advanced materials.
• Existing methods lack control over polymer initiation site placement on proteins.
• Homogeneous bioconjugates with defined structures are challenging to produce.

Purpose of the Study:

• To develop a general method for site-specific protein polymerization.
• To create a genetically encoded initiator for controlled polymer growth from proteins.
• To demonstrate the synthesis of homogeneous protein-polymer bioconjugates.

Main Methods:

• Designed and synthesized 4-(2'-bromoisobutyramido)phenylalanine as a polymer initiator.
• Evolved a tyrosyl-tRNA synthetase/tRNA(CUA) pair for genetic encoding of the initiator.
• Utilized amber codon suppression to site-specifically incorporate the initiator into green fluorescent protein (GFP).
• Performed atom-transfer radical polymerization (ATRP) using the modified protein as an initiator.

Main Results:

• Successfully synthesized the initiator amino acid.
• Established a genetic system for site-specific incorporation of the initiator into proteins.
• Produced green fluorescent protein with the initiator (GFP-1) site-specifically on its surface.
• Efficiently synthesized polymer-GFP bioconjugates via ATRP, with polymers attached at the defined site.

Conclusions:

• The developed method enables site-specific protein polymerization.
• This approach provides a general strategy for producing homogeneous protein-polymer bioconjugates.
• The genetically encoded initiator facilitates controlled polymer attachment to proteins, opening avenues for novel biomaterials.