title: Ether phospholipids and glycosylinositolphospholipids are not required for amastigote virulence or for inhibition of macrophage activation by Leishmania major.
abstract: Ether phospholipids are major components of the membranes of humans and Leishmania. In protozoan parasites they occur separately or as part of the glycosylphosphatidylinositol (GPI) anchor of molecules implicated in virulence, such as lipophosphoglycan (LPG), smaller glycosylinositolphospholipids (GIPLs), and GPI-anchored proteins. We generated null mutants of the Leishmania major alkyldihydroxyacetonephosphate synthase (ADS), the first committed step of ether lipid synthesis. Enzymatic analysis and comprehensive mass spectrometric analysis showed that ads1- knock-outs lacked all ether phospholipids, including plasmalogens, LPG, and GIPLs. Leishmania ads1- thus represents the first ether lipid-synthesizing eukaryote for which a completely null mutant could be obtained. Remarkably ads1- grew well and maintained lipid rafts (detergent-resistant membranes). In virulence tests it closely resembled LPG-deficient L. major, including sensitivity to complement and an inability to survive the initial phase of macrophage infection. Likewise it retained the ability to inhibit host cell signaling and to form infectious amastigotes from the few parasites surviving the establishment defect. These findings counter current proposals that GIPLs are required for amastigote survival in the mammalian host or that parasite lyso-alkyl or alkylacyl-GPI anchors are solely responsible for inhibition of macrophage activation.
authors.affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: Rachel
authors.initials: R
authors.lastname: Zufferey
authors.forename: Simon
authors.initials: S
authors.lastname: Allen
authors.forename: Tamara
authors.initials: T
authors.lastname: Barron
authors.forename: Deborah R
authors.initials: DR
authors.lastname: Sullivan
authors.forename: Paul W
authors.initials: PW
authors.lastname: Denny
authors.forename: Igor C
authors.initials: IC
authors.lastname: Almeida
authors.forename: Deborah F
authors.initials: DF
authors.lastname: Smith
authors.forename: Salvatore J
authors.initials: SJ
authors.lastname: Turco
authors.forename: Michael A J
authors.initials: MA
authors.lastname: Ferguson
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Beverley
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D000818:Animals; D006028:Glycosphingolipids / Q000172:deficiency / Q000502:physiology; D017261:Glycosylphosphatidylinositols / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D018320:Leishmania major / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D008262:Macrophage Activation / Q000502:physiology*; D008264:Macrophages / Q000469:parasitology / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010742:Phospholipid Ethers / Q000032:analysis; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D006028:Glycosphingolipids; D017261:Glycosylphosphatidylinositols; D010742:Phospholipid Ethers; C008290:lipophosphonoglycan; D019883:Alkyl and Aryl Transferases; C019654:alkylglycerone-phosphate synthase