title: A novel phospholipase from Trypanosoma brucei.
abstract: Phospholipase A(1) activities have been detected in most cells where they have been sought and yet their characterization lags far behind that of the phospholipases A(2), C and D. The study presented here details the first cloning and characterization of a cytosolic PLA(1) that exhibits preference for phosphatidylcholine (GPCho) substrates. Trypanosoma brucei phospholipase A(1) (TbPLA(1)) is unique from previously identified eukaryotic PLA(1) because it is evolutionarily related to bacterial secreted PLA(1). A T. brucei ancestor most likely acquired the PLA(1) from a horizontal gene transfer of a PLA(1) from Sodalis glossinidius, a bacterial endosymbiont of tsetse flies. Nano-electrospray ionization tandem mass spectrometry analysis of TbPLA(1) mutants established that the enzyme functions in vivo to synthesize lysoGPCho metabolites containing long-chain mostly polyunsaturated and highly unsaturated fatty acids. Analysis of purified mutated recombinant forms of TbPLA(1) revealed that this enzyme is a serine hydrolase whose catalytic mechanism involves a triad consisting of the amino acid residues Ser-131, His-234 and Asp-183. The TbPLA(1) homozygous null mutants generated here constitute the only PLA(1) double knockouts from any organism.
authors.affiliation: Wellcome Trust Biocentre, Division of Biological Chemistry and Molecular Microbiology, College of Life Sciences, University of Dundee, Scotland, UK.
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Richmond
authors.forename: Terry K
authors.initials: TK
authors.lastname: Smith
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D020134:Catalytic Domain; D003001:Cloning, Molecular; D003600:Cytosol / Q000201:enzymology; D019143:Evolution, Molecular; D006868:Hydrolysis; D008244:Lysophosphatidylcholines / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010713:Phosphatidylcholines / Q000378:metabolism; D010741:Phospholipases A / Q000235:genetics* / Q000378:metabolism*; D010802:Phylogeny; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014346:Trypanosoma brucei brucei / Q000201:enzymology* / Q000235:genetics
chemical_list: D008244:Lysophosphatidylcholines; D010713:Phosphatidylcholines; D011994:Recombinant Proteins; D010741:Phospholipases A