Diacylation of Peptides Enables the Construction of Functional Vesicles for Drug-Carrying Liposomes

Membrane-forming phospholipids are generated in cells by enzymatic diacylation of non-amphiphilic polar head groups. Analogous non-enzymatic processes may have been relevant at the origin of life and could have practical utility in membrane synthesis. However, aqueous head group diacylation is challenging in the absence of enzymes. The use of charged peptides instead of canonical phospholipid head groups offers advantages with respect to ease of acylation and chemical diversity. Here we demonstrate that native chemical ligation (NCL) enables in situ synthesis of diacylated lipopeptides (D-ALPs), which spontaneously self-assemble into micron-sized vesicles resembling cellular membranes. Diacylation occurs between non-amphiphilic peptides possessing an N-terminal cysteine, and acyl thioesters. Peptide head groups endow unique membrane functions, which is demonstrated by incorporation of an arginine-glycine-aspartic acid (RGD) motif, resulting in vesicle targeting to α_vβ₃ integrin-overexpressing cancer cells. The biocompatibility and functional group programmability of D-ALPs supports their broad utility as membrane mimetics.