Reconstruction of phospholipid synthesis by combing in vitro fatty acid synthesis and cell-free gene expression

Abstract

Phospholipid synthesis is a fundamental process that promotes cell propagation and, presently, is the most challenging issue in artificial cell research aimed at reconstituting living cells from biomolecules. Here, we constructed a cell-free phospholipid synthesis system that combines in vitro fatty acid synthesis and a cell-free gene expression system that synthesizes acyltransferases for phospholipid synthesis. Fatty acids were synthesized from acetyl-CoA and malonyl-CoA, then continuously converted into phosphatidic acids by the cell-free synthesized acyltransferases. Because the system can avoid the accumulation of synthetic intermediates that suppress the reaction, the yield of phospholipid has significantly improved from previous schemes (up to 400 {micro}M). Additionally, by adding enzymes for recycling CoA, we synthesized phosphatidic acids from acetic acid and bicarbonate as carbon sources. The constructed system is available to express the genes from pathogenic bacteria and to analyze the synthesized phospholipids. By encapsulating our system inside giant vesicles, it would be possible to construct the artificial cells in which the membrane grows and divides sustainably.