Neutral Lipids in Yeast: Synthesis, Storage and Degradation
Neutral lipids are defined as hydrophobic molecules lacking charged groups. In yeast triacylglycerols and steryl esters comprise the major part of neutral lipids. These storage lipids accumulate when cells are provided with an excess of nutrients. Since substantial amounts of neutral lipids cannot be incorporated into biomembranes, they are sequestered from the cytosolic environment in so-called lipid particles (lipid droplets). Upon requirement storage lipids are mobilized from this compartment by triacylglycerol lipases and steryl ester hydrolases. The respective degradation products serve as energy sources and/or building blocks for membrane formation. In this chapter the reader is introduced to different mechanisms of triacylglycerol- and steryl ester synthesis, storage of these lipids in lipid particles and their subsequent mobilization. Finally, major gaps in our current knowledge about neutral lipid metabolism and research needs for a better understanding of neutral lipid turnover are highlighted.