title: Phosphoethanolamine N-methyltransferase (PMT-1) catalyses the first reaction of a new pathway for phosphocholine biosynthesis in Caenorhabditis elegans.
abstract: The development of nematicides targeting parasitic nematodes of animals and plants requires the identification of biochemical targets not found in host organisms. Recent studies suggest that Caenorhabditis elegans synthesizes phosphocholine through the action of PEAMT (S-adenosyl-L-methionine:phosphoethanolamine N-methyltransferases) that convert phosphoethanolamine into phosphocholine. Here, we examine the function of a PEAMT from C. elegans (gene: pmt-1; protein: PMT-1). Our analysis shows that PMT-1 only catalyses the conversion of phosphoethanolamine into phospho-monomethylethanolamine, which is the first step in the PEAMT pathway. This is in contrast with the multifunctional PEAMT from plants and Plasmodium that perform multiple methylations in the pathway using a single enzyme. Initial velocity and product inhibition studies indicate that PMT-1 uses a random sequential kinetic mechanism and is feedback inhibited by phosphocholine. To examine the effect of abrogating PMT-1 activity in C. elegans, RNAi (RNA interference) experiments demonstrate that pmt-1 is required for worm growth and development and validate PMT-1 as a potential target for inhibition. Moreover, providing pathway metabolites downstream of PMT-1 reverses the RNAi phenotype of pmt-1. Because PMT-1 is not found in mammals, is only distantly related to the plant PEAMT and is conserved in multiple parasitic nematodes of humans, animals and crop plants, inhibitors targeting it may prove valuable in human and veterinary medicine and agriculture.
authors.affiliation: Divergence, Inc., 893 North Warson Rd, St. Louis, MO 63141, USA.
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Brendza
authors.forename: William
authors.initials: W
authors.lastname: Haakenson
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Cahoon
authors.forename: Leslie M
authors.initials: LM
authors.lastname: Hicks
authors.forename: Lavanya H
authors.initials: LH
authors.lastname: Palavalli
authors.forename: Brandi J
authors.initials: BJ
authors.lastname: Chiapelli
authors.forename: Merry
authors.initials: M
authors.lastname: McLaird
authors.forename: James P
authors.initials: JP
authors.lastname: McCarter
authors.forename: D Jeremy
authors.initials: DJ
authors.lastname: Williams
authors.forename: Michelle C
authors.initials: MC
authors.lastname: Hresko
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Jez
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000166:cytology / Q000201:enzymology* / Q000502:physiology; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008780:Methyltransferases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010641:Phenotype; D010713:Phosphatidylcholines / Q000096:biosynthesis*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D016415:Sequence Alignment; D013379:Substrate Specificity
chemical_list: D029742:Caenorhabditis elegans Proteins; D010713:Phosphatidylcholines; D010940:Plant Proteins; D008780:Methyltransferases; C102844:phosphoethanolamine methyltransferase