title: The Glycerol-3-Phosphate Acyltransferase TbGAT is Dispensable for Viability and the Synthesis of Glycerolipids in Trypanosoma brucei.
abstract: Glycerolipids are the main constituents of biological membranes in Trypanosoma brucei, which causes sleeping sickness in humans. Importantly, they occur as a structural component of the glycosylphosphatidylinositol lipid anchor of the abundant cell surface glycoproteins procyclin in procyclic forms and variant surface glycoprotein in bloodstream form, that play crucial roles for the development of the parasite in the insect vector and the mammalian host, respectively. The present work reports the characterization of the glycerol-3-phosphate acyltransferase TbGAT that initiates the biosynthesis of ester glycerolipids. TbGAT restored glycerol-3-phosphate acyltransferase activity when expressed in a Leishmania major deletion strain lacking this activity and exhibited preference for medium length, unsaturated fatty acyl-CoAs. TbGAT localized to the endoplasmic reticulum membrane with its N-terminal domain facing the cytosol. Despite that a TbGAT null mutant in T. brucei procyclic forms lacked glycerol-3-phosphate acyltransferase activity, it remained viable and exhibited similar growth rate as the wild type. TbGAT was dispensable for the biosynthesis of phosphatidylcholine, phosphatidylinositol, phosphatidylserine, and GPI-anchored protein procyclin. However, the null mutant exhibited a slight decrease in phosphatidylethanolamine biosynthesis that was compensated with a modest increase in production of ether phosphatidylcholine. Our data suggest that an alternative initial acyltransferase takes over TbGAT's function in its absence.
authors.affiliation: Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, New York, 11439.
authors.forename: Nipul
authors.initials: N
authors.lastname: Patel
authors.affiliation: Department of Biochemistry, Kansas State University, Manhattan, Kansas, 66506.
authors.forename: Karim A
authors.initials: KA
authors.lastname: Pirani
authors.affiliation: Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, New York, 11439.
authors.forename: Tongtong
authors.initials: T
authors.lastname: Zhu
authors.affiliation: Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, New York, 11439.
authors.forename: Melanie
authors.initials: M
authors.lastname: Cheung-See-Kit
authors.affiliation: Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, New York, 11439.
authors.forename: Sungsu
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, New York, 11439.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Chen
authors.affiliation: Department of Biological Sciences, St John's University, 8000 Utopia Parkway, Jamaica, New York, 11439.|Department of Biochemistry, Kansas State University, Manhattan, Kansas, 66506.
authors.forename: Rachel
authors.initials: R
authors.lastname: Zufferey
mesh_terms: D000217:Acyltransferases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D016054:DNA, Protozoan / Q000235:genetics; D004789:Enzyme Activation; D057075:Enzyme Assays; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000235:genetics / Q000378:metabolism*; D050356:Lipid Metabolism; D008055:Lipids / Q000096:biosynthesis* / Q000737:chemistry; D008562:Membrane Glycoproteins / Q000378:metabolism; D009154:Mutation; D010710:Phosphates / Q000378:metabolism; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000096:biosynthesis / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D010718:Phosphatidylserines / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D014346:Trypanosoma brucei brucei / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*
chemical_list: D016054:DNA, Protozoan; D008055:Lipids; D008562:Membrane Glycoproteins; D010710:Phosphates; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010716:Phosphatidylinositols; D010718:Phosphatidylserines; D015800:Protozoan Proteins; D012337:RNA, Ribosomal, 18S; C483858:phosphatidylethanolamine; D000217:Acyltransferases; D005992:Glycerol-3-Phosphate O-Acyltransferase
keywords: Cell fractionation; enzyme; immunofluorescence assay; mutant; trypanosomatid