title: The initial step of glycerolipid metabolism in Leishmania major promastigotes involves a single glycerol-3-phosphate acyltransferase enzyme important for the synthesis of triacylglycerol but not essential for virulence.
abstract: The synthesis of the major phospholipids, including those that play an essential role in Leishmania virulence, initiates with the acylation of glycerol-3-phosphate and dihydroxyacetonephosphate at the sn-1 position by glycerol-3-phosphate and dihydroxyacetonephosphate acyltransferases respectively. In this study, we show that Leishmania major promastigotes express a single glycerol-3-phosphate acyltransferase activity important for triacylglycerol synthesis but not essential for virulence. The encoding gene, LmGAT, expressed in yeast results in full complementation of the lethality of a mutant, gat1Deltagat2Delta, lacking glycerol-3-phosphate activity. Biochemical analyses revealed that LmGAT is a low-affinity glycerol-3-phosphate acyltransferase and exhibits higher specific activity with unsaturated long fatty acyl-CoA donors. A L. major null mutant, Deltalmgat/Deltalmgat, was created and a thorough analysis of its lipid composition was performed. Deletion of LmGAT resulted in a complete loss of Leishmania glycerol-3-phosphate acyltransferase activity and a major reduction in triacylglycerol synthesis. Consistent with the specificity of LmGAT for glycerol-3-phosphate but not dihydroxyacetonephosphate, Deltalmgat/Deltalmgat mutant expressed normal levels of the ether-lipid derivatives and virulence factors, lipophosphoglycan and GPI-anchored proteins, gp63, and its virulence was not affected in mice.
authors.affiliation: Center for Microbial Pathogenesis, University of Connecticut Health Center, 263 Farmington Ave, Farmington, CT 06030, USA.
authors.forename: Rachel
authors.initials: R
authors.lastname: Zufferey
authors.forename: Choukri Ben
authors.initials: CB
authors.lastname: Mamoun
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004099:Dihydroxyacetone Phosphate / Q000378:metabolism; D017125:Genes, Protozoan; D005989:Glycerides / Q000378:metabolism*; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000235:genetics / Q000378:metabolism*; D005994:Glycerophosphates / Q000378:metabolism; D006028:Glycosphingolipids / Q000378:metabolism; D007700:Kinetics; D018320:Leishmania major / Q000378:metabolism* / Q000472:pathogenicity* / Q000502:physiology; D016773:Leishmaniasis, Cutaneous / Q000469:parasitology; D008666:Metalloendopeptidases / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D013379:Substrate Specificity; D014280:Triglycerides / Q000096:biosynthesis*; D014774:Virulence / Q000502:physiology
chemical_list: D005989:Glycerides; D005994:Glycerophosphates; D006028:Glycosphingolipids; D014280:Triglycerides; C008290:lipophosphonoglycan; D004099:Dihydroxyacetone Phosphate; C029620:alpha-glycerophosphoric acid; D005992:Glycerol-3-Phosphate O-Acyltransferase; D008666:Metalloendopeptidases; C055146:glycoprotein gp63, Leishmania