Serinophospholipids:A Third Type of Natural PhospholipidDiscovered in a Thermophilic Bacterium

Phospholipids are an essential constituent of cells with all life thought to produce these compounds with either a glycerol or sphingoid moiety at their core. For the first time, we demonstrate that a thermophilic bacterium, <i>Limisphaera ngatamarikiensis</i> NGM72.4^T, produces a third type of phospholipid, serinophospholipids, which are distinct from glycero- and sphingophospholipids by featuring a serinol backbone instead. We show that the major serinophospholipid metabolites are <i>N</i>,<i>O</i>-diacylserinophospho-<i>N</i>-methylethanolamine and <i>N</i>,<i>O</i>-diacylserinophosphoethanolamine, and that serinophospholipids constitute up to 38% of the phospholipid mass. Furthermore, we demonstrate that these metabolites are further differentiated from “traditional” bacterial glycerophospholipids by their backbone configuration. In contrast to bacterial glycerophospholipids, which have an <i>sn</i>-glycerol-3-phosphate (G3P) architecture, the newly discovered serinophospholipids have an (<i>S</i>)-configured serinol core that is equivalent to the <i>sn-</i>glycerol-1-phosphate (G1P) arrangement characteristic of Archaea.