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A novel phospholipase from Trypanosoma brucei
Author(s) -
Richmond Gregory S.,
Smith Terry K.
Publication year - 2007
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2006.05582.x
Subject(s) - biology , trypanosoma brucei , biochemistry , phospholipase , mutant , catalytic triad , hydrolase , enzyme , serine , gene
Summary 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.