title: The bifunctional protein TtFARAT from Tetrahymena thermophila catalyzes the formation of both precursors required to initiate ether lipid biosynthesis.
abstract: The biosynthesis of ether lipids and wax esters requires as precursors fatty alcohols, which are synthesized by fatty acyl reductases (FARs). The presence of ether glycerolipids as well as branched wax esters has been reported in several free-living ciliate protozoa. In the genome of Tetrahymena thermophila, the only ORF sharing similarities with FARs is fused to an acyltransferase-like domain, whereas, in most other organisms, FARs are monofunctional proteins of similar size and domain structure. Here, we used heterologous expression in plant and yeast to functionally characterize the activities catalyzed by this protozoan protein. Transient expression in tobacco epidermis of a truncated form fused to the green fluorescence protein followed by confocal microscopy analysis suggested peroxisomal localization. In vivo approaches conducted in yeast indicated that the N-terminal FAR-like domain produced both 16:0 and 18:0 fatty alcohols, whereas the C-terminal acyltransferase-like domain was able to rescue the lethal phenotype of the yeast double mutant gat1Δ gat2Δ. Using in vitro approaches, we further demonstrated that this domain is a dihydroxyacetone phosphate acyltransferase that uses preferentially 16:0-coenzyme A as an acyl donor. Finally, coexpression in yeast with the alkyl-dihydroxyacetone phosphate synthase from T. thermophila resulted the detection of various glycerolipids with an ether bond, indicating reconstitution of the ether lipid biosynthetic pathway. Together, these results demonstrate that this FAR-like protein is peroxisomal and bifunctional, providing both substrates required by alkyl-dihydroxyacetone phosphate synthase to initiate ether lipid biosynthesis.
authors.affiliation: From the Université de Bordeaux, Laboratoire de Biogenèse Membranaire, UMR 5200, 33000 Bordeaux, France, the Centre National de la Recherche Scientifique, Laboratoire de Biogenèse Membranaire, UMR 5200, 33000 Bordeaux, France, and.
authors.forename: Franziska
authors.initials: F
authors.lastname: Dittrich-Domergue
authors.affiliation: From the Université de Bordeaux, Laboratoire de Biogenèse Membranaire, UMR 5200, 33000 Bordeaux, France, the Centre National de la Recherche Scientifique, Laboratoire de Biogenèse Membranaire, UMR 5200, 33000 Bordeaux, France, and.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Joubès
authors.affiliation: From the Université de Bordeaux, Laboratoire de Biogenèse Membranaire, UMR 5200, 33000 Bordeaux, France, the Centre National de la Recherche Scientifique, Laboratoire de Biogenèse Membranaire, UMR 5200, 33000 Bordeaux, France, and.
authors.forename: Patrick
authors.initials: P
authors.lastname: Moreau
authors.affiliation: From the Université de Bordeaux, Laboratoire de Biogenèse Membranaire, UMR 5200, 33000 Bordeaux, France, the Centre National de la Recherche Scientifique, Laboratoire de Biogenèse Membranaire, UMR 5200, 33000 Bordeaux, France, and.
authors.forename: René
authors.initials: R
authors.lastname: Lessire
authors.affiliation: the Department of Plant Breeding, Swedish University of Agricultural Sciences, P.O.B. 101, 23053 Alnarp, Sweden.
authors.forename: Sten
authors.initials: S
authors.lastname: Stymne
authors.affiliation: From the Université de Bordeaux, Laboratoire de Biogenèse Membranaire, UMR 5200, 33000 Bordeaux, France, the Centre National de la Recherche Scientifique, Laboratoire de Biogenèse Membranaire, UMR 5200, 33000 Bordeaux, France, and frederic.domergue@u-bordeaux.fr.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Domergue
mesh_terms: D000217:Acyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000445:Aldehyde Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004987:Ethers / Q000378:metabolism; D050939:Gene Fusion; D017125:Genes, Protozoan; D005816:Genetic Complementation Test; D008055:Lipids / Q000096:biosynthesis*; D010171:Palmitoyl Coenzyme A / Q000378:metabolism; D030821:Plants, Genetically Modified; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D016808:Tetrahymena thermophila / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism
chemical_list: D004987:Ethers; D008055:Lipids; D015800:Protozoan Proteins; D011994:Recombinant Proteins; D010171:Palmitoyl Coenzyme A; D000445:Aldehyde Oxidoreductases; D000217:Acyltransferases; C020051:glycerone-phosphate O-acyltransferase
keywords: Dihydroxyacetone Phosphate Acyltransferase; Fatty Acid Metabolism; Fatty Acyl Reductase; Functional Characterization; Fusion Protein; Gas Chromatography-Mass Spectrometry (GC-MS); Glycerophospholipid; Lipid Ether; Multifunctional Protein