Publications

• Developmentally regulated sphingolipid synthesis in African trypanosomes.

  Sutterwala S.S., Hsu F.F., Sevova E.S., Schwartz K.J., Zhang K., Key P., Turk J., Beverley S.M., Bangs J.D.

  Sphingolipids are essential components of eukaryotic membranes, and many unicellular eukaryotes, including kinetoplastid protozoa, are thought to synthesize exclusively inositol phosphorylceramide (IPC). Here we characterize sphingolipids from Trypanosoma brucei, and a trypanosome sphingolipid syn ... >> More

  Sphingolipids are essential components of eukaryotic membranes, and many unicellular eukaryotes, including kinetoplastid protozoa, are thought to synthesize exclusively inositol phosphorylceramide (IPC). Here we characterize sphingolipids from Trypanosoma brucei, and a trypanosome sphingolipid synthase gene family (TbSLS1-4) that is orthologous to Leishmania IPC synthase. Procyclic trypanosomes contain IPC, but also sphingomyelin, while surprisingly bloodstream-stage parasites contain sphingomyelin and ethanolamine phosphorylceramide (EPC), but no detectable IPC. In vivo fluorescent ceramide labelling confirmed stage-specific biosynthesis of both sphingomyelin and IPC. Expression of TbSLS4 in Leishmania resulted in production of sphingomyelin and EPC suggesting that the TbSLS gene family has bi-functional synthase activity. RNAi silencing of TbSLS1-4 in bloodstream trypanosomes led to rapid growth arrest and eventual cell death. Ceramide levels were increased more than threefold by silencing suggesting a toxic downstream effect mediated by this potent intracellular messenger. Topology predictions support a revised six-transmembrane domain model for the kinetoplastid sphingolipid synthases consistent with the proposed mammalian sphingomyelin synthase structure. This work reveals novel diversity and regulation in sphingolipid metabolism in this important group of human parasites. << Less

  Mol. Microbiol. 70:281-296(2008) [PubMed] [EuropePMC]

  This publication is cited by 5 other entries.

• Sphingomyelin synthase SMS2 displays dual activity as ceramide phosphoethanolamine synthase.

  Ternes P., Brouwers J.F., van den Dikkenberg J., Holthuis J.C.

  Sphingolipids are vital components of eukaryotic membranes involved in the regulation of cell growth, death, intracellular trafficking, and the barrier function of the plasma membrane (PM). While sphingomyelin (SM) is the major sphingolipid in mammals, previous studies indicate that mammalian cell ... >> More

  Sphingolipids are vital components of eukaryotic membranes involved in the regulation of cell growth, death, intracellular trafficking, and the barrier function of the plasma membrane (PM). While sphingomyelin (SM) is the major sphingolipid in mammals, previous studies indicate that mammalian cells also produce the SM analog ceramide phosphoethanolamine (CPE). Little is known about the biological role of CPE or the enzyme(s) responsible for CPE biosynthesis. SM production is mediated by the SM synthases SMS1 in the Golgi and SMS2 at the PM, while a closely related enzyme, SMSr, has an unknown biochemical function. We now demonstrate that SMS family members display striking differences in substrate specificity, with SMS1 and SMSr being monofunctional enzymes with SM and CPE synthase activity, respectively, and SMS2 acting as a bifunctional enzyme with both SM and CPE synthase activity. In agreement with the PM residency of SMS2, we show that both SM and CPE synthase activities are enhanced at the surface of SMS2-overexpressing HeLa cells. Our findings reveal an unexpected diversity in substrate specificity among SMS family members that should enable the design of specific inhibitors to target the biological role of each enzyme individually. << Less

  J. Lipid Res. 50:2270-2277(2009) [PubMed] [EuropePMC]

  This publication is cited by 11 other entries.

• Cryo-EM structure of human sphingomyelin synthase and its mechanistic implications for sphingomyelin synthesis.

  Hu K., Zhang Q., Chen Y., Yang J., Xia Y., Rao B., Li S., Shen Y., Cao M., Lu H., Qin A., Jiang X.C., Yao D., Zhao J., Zhou L., Cao Y.

  Sphingomyelin (SM) has key roles in modulating mammalian membrane properties and serves as an important pool for bioactive molecules. SM biosynthesis is mediated by the sphingomyelin synthase (SMS) family, comprising SMS1, SMS2 and SMS-related (SMSr) members. Although SMS1 and SMS2 exhibit SMS act ... >> More

  Sphingomyelin (SM) has key roles in modulating mammalian membrane properties and serves as an important pool for bioactive molecules. SM biosynthesis is mediated by the sphingomyelin synthase (SMS) family, comprising SMS1, SMS2 and SMS-related (SMSr) members. Although SMS1 and SMS2 exhibit SMS activity, SMSr possesses ceramide phosphoethanolamine synthase activity. Here we determined the cryo-electron microscopic structures of human SMSr in complexes with ceramide, diacylglycerol/phosphoethanolamine and ceramide/phosphoethanolamine (CPE). The structures revealed a hexameric arrangement with a reaction chamber located between the transmembrane helices. Within this structure, a catalytic pentad E-H/D-H-D was identified, situated at the interface between the lipophilic and hydrophilic segments of the reaction chamber. Additionally, the study unveiled the two-step synthesis process catalyzed by SMSr, involving PE-PLC (phosphatidylethanolamine-phospholipase C) hydrolysis and the subsequent transfer of the phosphoethanolamine moiety to ceramide. This research provides insights into the catalytic mechanism of SMSr and expands our understanding of sphingolipid metabolism. << Less

  Nat. Struct. Mol. Biol. 31:884-895(2024) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.