Display of membrane proteins on the recombinant endosome induced by caveolin1 in Escherichia coli

Caveolae is a membrane-budding structure which exists in many animal vertebrate cells. One of the important functions of caveolae is to form membrane curvature and endocytic vesicle. Recently, it was shown that caveolae and recombinant endosome (rEndosome) could be formed in Escherichia coli by expressing caveolin-1. The rEndosome may host other membrane proteins overexpressed inside the cell. We utilized this system for construction of proteo-liposome in E. coli. SNARE proteins (Syntaxin1a, SNAP25, VAMP2) were introduced to prove our in vivo endosome display system. Purified rEndosome indeed contained the co-expressed membrane proteins and the membrane protein were facing outward. The size of the purified rEndosomes were 100nm diameter when measured by dynamic light scattering. The presence of VAMP2 & Syntaxin1a on this proteo-endosome was confirmed by Western blot analysis. Furthermore, membrane proteins (VAMP2 & Syntaxin1) embedded in rEndosome retained its ability to drive membrane fusion. Our study proposes in vivo recombinant endosome display system.