Abstract
Living cells segregate molecules and reactions in various subcellular compartments and locations. Spatial organization is likely essential for expanding the biochemical functions of synthetic reaction systems, including artificial cells. Here we describe programmable synthetic organelles based on highly stable lipid sponge phase droplets that spontaneously assemble from a galactose-derived single-chain lipid and non-ionic detergents. Fluorescent dyes and biologically relevant molecules partition into droplets based on their size, polarity, and specific binding motifs. The sequestration of macromolecules can be further programmed by the addition of suitably functionalized amphiphiles to the droplets. We demonstrate that droplets can harbor functional soluble and transmembrane proteins, allowing for the co-localization and concentration of enzymes and substrates to enhance reaction rates. Droplets protect bound proteins from proteases, and these interactions can be engineered to be reversible and optically controlled. Lipid sponge droplets permit the facile introduction of membrane environments and self-assembling spatial organization into biochemical reaction systems.