Selective Recognition, Covalent Linkage and Chemical Exchange of Artificial Cells through Engineered α-Hemolysin
Bottom-up synthetic biology aims not only to build individual artificial cells but also to connect them into higher-order systems that communicate with each other. Reported artificial cells communicate through partner recognition, physical connection, and chemical signaling that are typically implemented by separate molecular species. Here, we engineer the pore-forming protein -hemolysin (AH) with the SpyTag-SpyCatcher (ST-SC) pair to integrate partner recognition, covalent linkage between cells, and nanopore-mediated connection of their lumens into a single protein system. Fusion of ST or SC to AH preserved heptamer assembly and pore formation, and allowed the two heptamers (AH-ST and AH-SC) to be covalently joined. Cryo-electron microscopy resolved the resulting head-to-head 14-mer assembly at 2.20 [A]. Calcein leakage and single-channel recordings confirmed that the engineered pores remain functional. Mixing ST- and SC-displaying giant unilamellar vesicles (GUVs) resulted in partner-specific association between the two vesicle populations. Finally, photo-triggered release of a newly synthesized caged ethidium bromide (EtBr) in sender GUVs produced EtBr accumulation in receiver GUVs that required direct physical linkage between the two GUVs. This platform provides a modular route toward artificial-cell assemblies in which both connectivity and cargo exchange are programmable.