Genetically Encoding Light‐Responsive Protein‐Polymers Using Translation Machinery for the Multi‐Site Incorporation of Photo‐Switchable Unnatural Amino Acids

A general and versatile technology to engineer light‐responsive protein‐based biomaterials can enable the manipulation and interrogation of proteins, pathways, and cells, and it will assist the design of “smart” light‐responsive biomaterials. This study reports the evolution of chromosomal aminoacyl‐tRNA synthetases (aaRSs) for azobenzene‐bearing unnatural amino acids (uAAs) with up to ≈40‐fold increased protein production and improved fidelity, as compared with a previously described aaRS. The evolved translation systems enable efficient and accurate incorporation of up to 10 instances of the various light‐responsive uAAs in elastin‐like polypeptides (ELPs). Azobenzene‐containing ELPs are capable of isothermal, reversible, light‐mediated soluble‐to‐insoluble phase transition, with up to a 12 °C difference in the ELP transition temperature upon cis‐to‐trans azobenzene isomerization. Furthermore, the incorporation of azobenzene‐uAAs in ELP diblock‐copolymers enables the creation of light‐responsive self‐assembled nanostructures. Finally, light‐responsive resilin‐inspired polymers are also generated by multi‐site azobenzene‐incorporation. The translation machinery evolved in this study can be used for the multi‐site incorporation of azobenzene moieties at the polypeptide level and constitute a universal methodology for the design of light‐responsive proteins and additional families of protein‐based biomaterials with customized and tunable light‐responsive behavior. Translation machinery for the multi‐site incorporation of UV and visible light‐responsive azobenzene‐bearing unnatural amino acids (uAAs) into proteins are produced. Azobenzene‐uAA incorporation in protein‐based polymers generates a reversible and isothermal light‐responsive phase transition and self‐assembly behavior that can be tuned by the identity of the azobenzene‐uAAs and their number and position in the protein sequence.