Temperature adaptation of yeast phospholipid molecular species at the acyl chain positional level

The budding yeast Saccharomyces cerevisiae is a poikilothermic organism and adapts its lipid composition to the environmental temperature to maintain membrane physical properties. Studies addressing temperature-dependent adaptation of the lipidome in yeast have described changes in the phospholipid composition at the level of sum composition (e.g. PC 32:1) and molecular composition (e.g. PC 16:0_16:1). However, to date, there is no information at the level of positional isomers (e.g. PC 16:0/16:1 versus PC 16:1/16:0). In this study, combined Collision- and Ozone-Induced Dissociation (CID/OzID) mass spectrometry was deployed to investigate homeoviscous adaptation of PC, PE, and PS sn-molecular species composition. We determined the main species to be 16:1/16:1, 16:0/16:1, 16:1/18:1, 16:0/18:1, and 18:0/16:1. In general, at higher culture temperature, the sn-1 position is increased in saturated acyl chains, whereas the sn-2 position mainly is increased in acyl chain length. PC mainly increases in 16:0/16:1 and 16:0/18:1, at the expense of 16:1/16:1, whereas PS and PE increase in 16:1/18:1, at the expense of 16:1/16:1 and 16:0/16:1. Our data suggest distinct adaptation mechanisms of the sn-1 and sn-2 acyl chains, and different manners of sn-molecular species adaptation between PC and PE/PS.