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Phosphatidylcholine Biosynthesis in Plants and Nematodes: Biochemical and Thermodynamic Characterization of Phosphoethanolamine Methyltransferases
Author(s) -
Lee SoonGoo,
Jez Joseph M.
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.554.2
Phosphoethanolamine N‐methyltransferases (PMT) catalyze the triple methylation of phosphoethanolamine to produce phosphocholine (pCho) in plants and Plasmodium falciparum . Recent studies suggest that Caenorhabditis elegans synthesizes pCho through the action of two PMT enzymes, PMT‐1 and PMT‐2. Although the basic steps of the phosphobase methylation pathway are understood, the molecular mechanisms and the evolution of the different classes of PMT are not. To systematically analyze the biochemical and binding properties of PMT, three type I PMT from Arabidopsis thaliana and two type III PMT from a parasitic nematode Haemonchus contortus were isolated and characterized. Our biochemical studies show that two PMT from H. contortus are required to complete the multiple methylations in the pathway in contrast to the multifunctional PMT. Further, we have characterized binding of PMT with S‐adenosylhomocysteine (SAH) using isothermal titration calorimetry. The results suggest that both type I and type III PMT bind to SAH with similar affinities but different stoichiometries, indicating the presence of the consensus SAM‐binding motifs with the different organization of the methyltransferase domains. Future work will examine the structural difference of each PMT by determining the three‐dimensional structure by x‐ray crystallography.