Assessing the efficacy of vesicle fusion with planar membrane arrays using a mitochondrial porin as reporter

Reconstitution of functionally active membrane protein into artificially made lipid bilayers is a challenge that must be overcome to create a membrane-based biomimetic sensor and separation device. In this study we address the efficacy of proteoliposome fusion with planar membrane arrays. We establish a protein incorporation efficacy assay using the major non-specific porin of Fusobacterium nucleatum (FomA) as reporter. We use electrical conductance measurements and fluorescence microscopy to characterize proteoliposome fusion with an array of planar membranes. We show that protein reconstitution in biomimetic membrane arrays may be quantified using the developed FomA assay. Specifically, we show that FomA vesicles are inherently fusigenic. Optimal FomA incorporation is obtained with a proteoliposome lipid-to-protein molar ratio (LPR) = 50 more than 105 FomA proteins could be incorporated in a bilayer array with a total membrane area of 2 mm2 within 20 min. This novel assay for quantifying protein delivery into lipid bilayers may be a useful tool in developing biomimetic membrane applications.

Research highlights
► We have established a vesicle fusion efficacy assay based on the major non-specific porin of Fusobacterium nucleatum (FomA).
► Maximal fusion obtained was almost 150,000 porin insertions during 20 min.
► Incorporation can be either first order or exponential kinetics which has implications for establishing protein delivery to biomimetic membranes.