Dynamically Tunable, Macroscopic Molecular Networks Enabled by Cellular Synthesis of 4-Arm Star-like Proteins

Summary Design of proteins with nonlinear topologies has emerged as a nascent branch of protein engineering, but significant applications remain to be seen. Here, we demonstrate the cellular synthesis of (SpyCatcher)4GFP, a 4-arm star-like protein enabled by spontaneous split GFP reconstitution, which further led to the creation of various protein networks exhibiting tunable mechanics and suitability for cell encapsulation. A derivative 4-arm star-like protein, (CarHC)4GFP, resulting from the conjugation of (SpyCatcher)4GFP with the SpyTag-fusion CarHC photoreceptors, can undergo rapid sol-gel and gel-sol transitions in response to AdoB12 and light, respectively. The chemo- and photo-induced phase transitions enabled encapsulation and controlled release of protein molecules such as the biofilm-degrading glycosyl hydrolase PslG, a potential agent for combatting multidrug-resistant bacterial species in chronic infections. The creation of those uncommon protein architectures promises great opportunities for materials biology and "smart" therapeutic delivery.