Membrane contact sites; Phospholipids; Phosphatidylethanolamine; Respiratory chain complexes; Trypanosoma brucei; Mitochondrion; Cardiolipin
Dawoody Nejad Ladan, Stumpe Michael, Rauch Monika, Hemphill Andrew, Schneiter Roger, Bütikofer Peter, Serricchio Mauro (2020), Mitochondrial sphingosine-1-phosphate lyase is essential for phosphatidylethanolamine synthesis and survival of Trypanosoma brucei, in Scientific Reports
, 10(1), 8268-8268.
Serricchio Mauro, Hierro‐Yap Carolina, Schädeli David, Ben Hamidane Hisham, Hemphill Andrew, Graumann Johannes, Zíková Alena, Bütikofer Peter (2020), Depletion of cardiolipin induces major changes in energy metabolism in Trypanosoma brucei bloodstream forms, in The FASEB Journal
Schädeli David, Serricchio Mauro, Ben Hamidane Hisham, Loffreda Alessio, Hemphill Andrew, Beneke Tom, Gluenz Eva, Graumann Johannes, Bütikofer Peter (2019), Cardiolipin depletion–induced changes in the Trypanosoma brucei proteome, in The FASEB Journal
, 33(12), 13161-13175.
Jelk Jennifer, Balmer Vreni, Stibal David, Giannini Federico, Süss-Fink Georg, Bütikofer Peter, Furrer Julien, Hemphill Andrew (2019), Anti-parasitic dinuclear thiolato-bridged arene ruthenium complexes alter the mitochondrial ultrastructure and membrane potential in Trypanosoma brucei bloodstream forms, in Experimental Parasitology
, 205, 107753-107753.
Wang Lei, Iwasaki Yugo, Andra Kiran K., Pandey Kalpana, Menon Anant K., Bütikofer Peter (2018), Scrambling of natural and fluorescently tagged phosphatidylinositol by reconstituted G protein–coupled receptor and TMEM16 scramblases, in Journal of Biological Chemistry
, 293(47), 18318-18327.
Dawoody Nejad Ladan, Serricchio Mauro, Jelk Jennifer, Hemphill Andrew, Bütikofer Peter (2018), TbLpn, a key enzyme in lipid droplet formation and phospholipid metabolism, is essential for mitochondrial integrity and growth of Trypanosoma brucei Role of lipin in T. brucei growth, in Molecular Microbiology
, 109(1), 105-120.
Gottier Petra, Serricchio Mauro, Vitale Rita, Corcelli Angela, Buetikofer Peter (2017), Cross-species complementation of bacterial- and eukaryotic-type cardiolipin synthases, in Microbial Cell
, 4(11), 376-383.
Trypanosoma brucei is the causative agent of human African sleeping sickness and nagana, a related livestock disease, in sub-Saharan Africa. During their life cycle, T. brucei parasites live in the blood and extracellular fluids of the mammalian hosts and colonize several organs in the insect vector, the tsetse fly. Because T. brucei can be cultured axenically in vitro and is amenable to reverse genetics, including inducible RNAi-mediated silencing of gene expression and gene knock-out by homologous recombination, it is often used as model organism for molecular parasitology. However, T. brucei has also emerged as unicellular model eukaryote to study general biological processes, including mitochondrial function and membrane lipid metabolism. The main research focus of our laboratory is on the identification and characterization of the pathways of glycerophospholipid synthesis in T. brucei, to reveal their importance for parasite viability and to gain further insight into mechanisms involved in eukaryotic glycerophospholipid homeostasis. In addition, we are interested to study the roles of membrane lipids in protein function in the trypanosome mitochondrion.It has been shown in other eukaryotes that the stability and activity of mitochondrial respiratory chain complexes and the generation of the mitochondrial membrane potential is dependent on the presence of the mitochondrial signature lipid cardiolipin (CL) in the inner mitochondrial membrane. By using our T. brucei cell lines in which we can induce changes in the levels of CL and of its biosynthetic precursor phosphatidylglycerol (PG), we have recently been able to demonstrate similar events in trypanosomes. In the first part of the proposal, we plan to use these cells in combination with an unbiased approach to identify novel CL-dependent proteins and study their importance for mitochondrial function. The fact that the mitochondrion in T. brucei undergoes major morphological and functional changes during differentiation between different life cycle forms provides a unique opportunity to study such questions under two metabolically very different conditions, i.e. in the absence or presence of key mitochondrial components and functions. In addition, we will exploit our preliminary observations that two key enzymes in mitochondrial glycerophospholipid synthesis, TbPGPS and TbCLS, are likely present in the same high molecular mass protein complex and propose to identify their interaction partners. Finally, identification of the substrates of TbPGPS and TbCLS, which may lead to the discovery of a novel catalytic mechanism for PG formation, completes this main part of the grant application.In the second part, we will focus on de novo synthesis of phosphatidylethanolamine (PE) via the CDP-ethanolamine branch of the Kennedy pathway, a reaction sequence that we have previously shown to be essential for T. brucei viability. Since the initial reactions to produce the lipophilic substrate for PE synthesis occur in glycosomes whereas the terminal reaction takes place in the perinuclear endoplasmic reticulum, we plan to localize all intermediate enzymatic steps to obtain a complete map for PE synthesis in T. brucei. Such a comprehensive analysis of the route for PE formation has not been undertaken in any eukaryote before.The third part of the proposal is based on our very recent observations aimed at elucidating contact sites between the endoplasmic reticulum and the mitochondrion to understand membrane lipid trafficking between these two organelles. We have localized homologs of an endoplasmic reticulum-mitochondrion tethering complex in T. brucei and found that down-regulation of a single component of this complex causes a growth defect of trypanosomes. We will study a possible connection of this complex with a highly purified T. brucei membrane fraction that resembles mitochondria-associated membranes described previously in other eukaryotes. Preliminary proteomic and lipidomic analyses suggest the involvement of this fraction in lipid synthesis and transport in T. brucei parasites.