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.
| Original language | English |
|---|---|
| Pages (from-to) | 1078-95 |
| Number of pages | 18 |
| Journal | Molecular Microbiology |
| Volume | 63 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - Feb 2007 |
Keywords
- Amino Acid Sequence
- Animals
- Base Sequence
- Catalytic Domain
- Cloning, Molecular
- Cytosol
- Evolution, Molecular
- Hydrolysis
- Lysophosphatidylcholines
- Molecular Sequence Data
- Mutation
- Phosphatidylcholines
- Phospholipases A
- Phylogeny
- Recombinant Proteins
- Sequence Homology, Amino Acid
- Substrate Specificity
- Trypanosoma brucei brucei