Vacuole-specific lipid release for tracking intracellular lipid metabolism and transport in Saccharomyces cerevisiae
Lipid metabolism is spatiotemporally regulated within cells, yet intervention into lipid functions at subcellular resolution remains difficult. Here we report a method that enables site-specific release of sphingolipids and cholesterol inside the vacuole in Saccharomyces cerevisiae. Using this approach, we monitored real-time sphingolipid metabolic flux out of the vacuole by mass spectrometry and found that the ER-vacuole tethering protein Mdm1 facilitated the metabolism of sphingoid bases into ceramides. In addition, we showed that cholesterol, once delivered into yeast using our method, could restore cell proliferation induced by ergosterol deprivation, overcoming the previously described sterol-uptake barrier under aerobic conditions. Together, these data define a new way to study intracellular lipid metabolism and transport from the vacuole in yeast.