Mechanisms of ceramide sorting and transport between the endoplasmic reticulum and the Golgi apparatus in Saccharomyces cerevisiae.

• Applicant: Professor Dr. Florian Fröhlich
• Subject Area: Biochemistry
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 464504472

Ceramides are an important class of lipids in all eukaryotic cells. They act as signaling molecules and are precursors of complex sphingolipids, which function as structural components of the plasma membrane. To be converted into complex sphingolipids, ceramides must be transported from the endoplasmic reticulum (ER) to the Golgi apparatus. In mammalian cells, this step is mainly carried out through non-vesicular transport via the ceramide transport protein CERT. In Saccharomyces cerevisiae, ceramides are transported both, by vesicular and non-vesicular transport. However, the molecular mechanisms of ceramide transport in yeast are largely unknown. During the first funding period, we were able to show that Svf1 binds to the Golgi via an amphipathic helix and can uptake ceramides from the membrane through a hydrophobic pocket. This suggests that Svf1 is indeed a ceramide transfer protein in yeast. However, the mechanism of ceramide uptake and transfer, as well as the function of the two Svf1 homologs in yeast, remain unknown. In this project, we plan to elucidate the molecular mechanism of ceramide transfer using in vitro reconstitution. Additionally, we plan to use structural biology analyses to better understand the mechanism of ceramide uptake. Furthermore, we aim to decipher the functions of the Svf1 homologs in yeast. This will help to elucidate the molecular mechanisms of lipocalin domains in ceramide transfer.

• DFG Programme: Research Grants