Liposomes Mediated Synthesis of Membrane Proteins
Synthetic biology is an emerging field that aims at constructing artificial biological systems by combining engineering and molecular biology approaches. One of the most ambitious research line concerns the socalled semi-synthetic minimal cells, which are liposome-based system capable of synthesizing the lipids within the liposome surface. This goal can be reached by reconstituting membrane proteins within liposomes and allow them to synthesize lipids. This approach, that can be defined as biochemical, was already reported by Schmidli et al. (in 1991). In more advanced models, however, a full reconstruction of the biochemical pathway requires (1) the synthesis of functional membrane enzymes inside liposomes, and (2) the local synthesis of lipids as catalyzed by the in situ synthesized enzymes. Here we show the synthesis and the activity – inside liposomes – of two membrane proteins involved in phospholipids biosynthesis pathway. The proteins, sn-glycerol-3-phosphate acyltransferase (GPAT) and lysophosphatidic acid acyltransferase (LPAAT), have been synthesized by using a totally reconstructed cell-free system (PURE system) encapsulated in liposomes. The activities of internally synthesized GPAT and LPAAT were confirmed by detecting the produced lysophosphatidic acid and phosphatidic acid, respectively. Through this procedure, we have implemented the first phase of a design aimed at synthesizing phospholipid membrane from liposome within – which corresponds to the autopoietic growth mechanism.
KeywordsLiposomes Membrane protein Cell-free translation system Lipid synthesis Minimal cells
- Luisi PL (2006) The emergence of life. From chemical origins to synthetic biology. Cambridge University Press, CambridgeGoogle Scholar
- Nomura SM, Tsumoto K, Hamada T, Akiyoshi K, Nakatani Y, Yoshikawa K (2003) Gene expression within cell-sized lipid vesicles. Chembiochem 4:1172–1175Google Scholar
- Schmidli PK, Schurtenberger P, Luisi PL (1991) Liposome-mediated enzymatic synthesis of phosphatidylcholine as an approach to self-replicating liposomes. J Am Chem Soc 113:8127–8130Google Scholar