University of Osnabrueck, Germany
28 June 2023 at 14:30:00
Structural and functional characterization of sphingolipid metabolic enzymes
Sphingolipids constitute one of the three major lipid classes found in all eukaryotic cells. They play a crucial role in the functional organization of the plasma membrane and serve as signaling molecules. Consequently, sphingolipid levels need to be tightly controlled and adjusted according to need. Although we possess a comprehensive understanding of the enzymes involved in yeast sphingolipid synthesis, our knowledge regarding the molecular mechanisms governing their regulation remains limited. To address this gap, we have recently embarked on a molecular-level investigation of these processes. Specifically, we purify the metabolic enzymes responsible for yeast sphingolipid metabolism and subject them to structural analysis using cryo-electron microscopy. We have successfully elucidated the structure of the yeast serine palmitoyl transferase (SPT) in complex with the small subunit Tsc3, the negative regulator Orm1, and the phosphatidyl-inositol-4-phosphate phosphatase Sac1 (referred to as the SPOTS complex). Our structure unravels the intricate interplay between Orm proteins and ceramide, a downstream metabolite, in inhibiting SPT activity. Expanding our workflow, we are now investigating other yeast sphingolipid metabolic enzymes to gain deeper insights into their molecular mechanisms and regulation. Given the high evolutionary conservation of most of these enzymes, our analyses also enable us to make predictions regarding the regulation of human sphingolipid metabolism.