Stability of Heterochiral Hybrid Membrane Made of Bacterial sn-G3P Lipids and Archaeal sn-G1P Lipids

摘要

The structure ofmembrane lipids in Archaea is different fromthose of Bacteria and Eucarya innmany ways including the chirality of the glycerol backbone. Until now, heterochiral membranes werenbelieved to be unstable; thus, no cellular organism could have existed before the separation of the groups ofnlife. In this study, we tested the formation of heterochiral hybrid membrane made of Bacterial sn-glycerol-3-nphosphate-type polar lipid and Archaeal sn-glycerol-1-phosphate-type polar lipid using the fluorescencenprobe. The stability of the hybrid liposomesmade of phosphatidylethanolamines or phosphatidylcholines ornpolar lipids of thermophilic Bacteria and polar lipids of Archaea were investigated. The hybrid liposomes arenall stable compared with homochiral liposome made of dimyristoylphosphatidylethanolamine and dipalmi-ntoylphosphatidylcholine. However, the stability was drastically changed with increasing carbon chain length.nAccordingly, “chirality” may not be but chain length is important. From these results, we suggest that thenheterochiral hybrid membrane could be used as the membrane lipid for the last universal common ancestor (Commonote) beforenthe emergence of Archaea and Bacteria.