Spatial Positioning and Chemical Coupling in Coacervate-in-Proteinosome Protocells

The integration of molecularly crowded micro-environments into membrane-enclosed protocell models represents a step towards more realistic representations of cellular structure and organization. Herein, the membrane diffusion-mediated nucleation of negatively or positively charged coacervate micro-droplets within the aqueous lumen of individual proteinosomes is used to prepare nested hybrid protocells with spatially organized and chemically coupled enzyme activities. The location and reconfiguration of the entrapped droplets are regulated by tuning the electrostatic interactions between the encapsulated coacervate and surrounding negatively charged proteinosome membrane. As a consequence, alternative modes of a cascade reaction involving membrane- and coacervate-segregated enzymes can be implemented within the coacervate-in-proteinosome protocells.