Phospholipids are the main lipid components of cellular membranes. Their unique properties make them especially attractive for a range of applications, including the study of protein-membrane interactions, origins-of-life research, and the fabrication of novel artificial cell models. However, the biosynthesis of phospholipids involves elaborate pathways mediated by numerous complex enzymes that are challenging to fully reconstitute in vitro. Consequently, one of the major goals in biomimetic chemistry is the development of chemoselective approaches for the construction of phospholipids, which will shed light on how nature builds living systems. Chemoselective control in phospholipid synthesis aims to design a strategy for two lipid precursors to predominantly form a phospholipid product. Therefore, a chemoselective strategy must adopt innovative chemistries having high yield, desirable reactivity, and selectivity. Recently, two amide bond-forming reactions have been discovered using hydroxylamine and acyltrifluoroborate or ketoacid precursors. We have adopted these two non-enzymatic and chemoselective amide-forming ligations to rapidly prepare phospholipids in situ using hydroxylamine-containing lysophospholipids and different long-chain acyl precursors (potassium palmitoylacyltrifluoroborate and 2-oxoxheptadecanoic acid). The corresponding phospholipids spontaneously self-assemble into micron-sized vesicles. As these approaches do not necessitate coupling reagents or cytotoxic organic solvents and do not produce toxic byproducts, they are compatible with biological systems. Due to the high selectivity and biocompatibility of the approach, we have demonstrated the high selectivity and biocompatibility of these approaches by synthesizing biomimetic phosphpolipids in situ in living cells. Thus, our strategy can be used to control the formation of phospholipids both in vitro and in vivo and has potential application in generating membrane-bound compartments as advanced synthetic cells.

<i>De novo</i> formation of phospholipid membranes using chemoselective amide-forming ligations.

De novo formation of phospholipid membranes using chemoselective amide-forming ligations.

Neal Devaraj

University of California San Diego

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