Biomimetic cell structures: Probing Induced pH-Feedback Loops and pH Self-Monitoring in Cytosol Using Binary Enzyme-loaded Polymersomes in Proteinosome

Abstract

Structures and functions of eukaryotic cells with an outer permeable membrane, motility, a cytoskeleton, biomolecules diffusion, and functional organelles can be imitated by a multi-compartmentalized and large-sized protocell containing various synthetic organelles. Herein, two kinds of artificial organelles with stimuli-trigged regulation ability, glucose oxidase-(GOx)-loaded pH-responsive polymersomes A (GOx-Psomes A) and urease-loaded pH-responsive polymersomes B (Urease-Psomes B) for probing biomimetic pH homeostasis, and a pH-sensor (Dextran-FITC) are encapsulated into proteinosomes by Pickering emulsion method. Thus, the polymersomes-in-proteinosome system is realized. Alternating input-regulation of fuels (glucose or urea) outside the protocell penetrates the membrane of proteinosomes and enters into GOx-Psomes A and Urease-Psomes B to produce chemical\biological signals (gluconic acid or ammonia) resulting in pH-feedback loops (pH jump and pH drop). This will counteract the catalytic “switch on” or “switch off” of enzyme-loaded Psomes A and B owing to their different pH-responsive membranes. Thus, the Dextran-FITC promotes a controlled cytosolic spatial organization and the detection of slight pH fluctuations in the lumen of protocells. Overall, this approach shows heterogeneous polymersome-in-proteinosome architectures with sophisticated features such as induced input-regulated pH changes mediated by negative/positive feedback in loops and cytosolic pH self-monitoring, requirements strictly needed in an advanced protocell design.

Construction of Membraneless and Multicompartmentalized Coacervate Protocells Controlling a Cell Metabolism-like Cascade Reaction

“…Furthermore, AF4-LS reveals the first indication for the incorporation of few enzymes into the membrane of the HFF-purified polymersomes due to the presence of heterogeneous Psomes surfaces, in agreement with previous studies. 58,73,75 Enzymes are also located in the lumen of Psomes. Further details on the enzyme location can be extracted only by the pH-dependent ALP activity later.…”