Morphological change of the phospholipid vesicle induced by actin polymerization of the artificial photosynthetic protocellular system.

We designed, built, and tested a light-harvesting encapsulated artificial organelle system that provides both a sustainable energy source and a means of controlling intracellular reactions. With the reconstitution into lipid vesicles, an ATP synthase and two photoconverters (plant-derived photosystem II [PSII] and bacteria-derived proteorhodopsin [PR]) enabled orchestration of ATP synthesis. Independent activation of the two photoconverters, which respond to different light wavelengths, allowed dynamic regulation of ATP synthesis. The resulting system was able to simulate a ubiquitous process in cells—cytoskeleton formation through ATP-dependent actin polymerization in a giant vesicle. Optical stimulation initiated ATP synthesis and induced ATP-dependent actin polymerization, leading to growth of three-dimensional actin filaments. Cytoskeleton formation and manipulation successfully induced morphological change of the outer membrane of the protocellular system by tuning the attraction–repulsion interactions between actin filaments and phospholipids.