Live Follow-Up of Enzymatic Reactions Inside the Cavities of Synthetic Giant Unilamellar Vesicles Equipped with Membrane Proteins Mimicking Cell Architecture.

Compartmentalization of functional biological units, cells, and organelles serves as an inspiration for the development of biomimetic materials with unprecedented properties and applications in biosensing and medicine. Because of the complexity of cells, the design of ideal functional materials remains a challenge. An elegant strategy to obtain cell-like compartments as novel materials with biofunctionality is the combination of synthetic micrometer-sized giant unilamellar vesicles (GUVs) with biomolecules because it enables studying the behavior of biomolecules and processes within confined cavities. Here we introduce a functional cell-mimetic compartment formed by insertion of the model biopore bacterial membrane protein OmpF in thick synthetic membranes of an artificial GUV compartment that encloses-as a model-the oxidative enzyme horseradish peroxidase. In this manner, a simple and robust cell mimic is designed: the biopore serves as a gate that allows substrates to enter cavities of the GUVs, where they are converted into products by the encapsulated enzyme and then released in the environments of GUVs. Our bioequipped GUVs facilitate the control of specific catalytic reactions in confined microscale spaces mimicking cell size and architecture and thus provide a straightforward approach serving to obtain deeper insights into biological processes inside cells in real time.