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Identification of Phosphomethylethanolamine N-Methyltransferase from Arabidopsis and Its Role in Choline and Phospholipid Metabolism
- Source :
- Journal of Biological Chemistry. 285:29147-29155
- Publication Year :
- 2010
- Publisher :
- Elsevier BV, 2010.
-
Abstract
- Three sequential methylations of phosphoethanolamine (PEA) are required for the synthesis of phosphocholine (PCho) in plants. A cDNA encoding an N-methyltransferase that catalyzes the last two methylation steps was cloned from Arabidopsis by heterologous complementation of a Saccharomyces cerevisiae cho2, opi3 mutant. The cDNA encodes phosphomethylethanolamine N-methyltransferase (PMEAMT), a polypeptide of 475 amino acids that is organized as two tandem methyltransferase domains. PMEAMT shows 87% amino acid identity to a related enzyme, phosphoethanolamine N-methyltransferase, an enzyme in plants that catalyzes all three methylations of PEA to PCho. PMEAMT cannot use PEA as a substrate, but assays using phosphomethylethanolamine as a substrate result in both phosphodimethylethanolamine and PCho as products. PMEAMT is inhibited by the reaction products PCho and S-adenosyl-l-homocysteine, a property reported for phosphoethanolamine N-methyltransferase from various plants. An Arabidopsis mutant with a T-DNA insertion associated with locus At1g48600 showed no transcripts encoding PMEAMT. Shotgun lipidomic analyses of leaves of atpmeamt and wild-type plants generated phospholipid profiles showing the content of phosphatidylmethylethanolamine to be altered relative to wild type with the content of a 34:3 lipid molecular species 2-fold higher in mutant plants. In S. cerevisiae, an increase in PtdMEA in membranes is associated with reduced viability. This raises a question regarding the role of PMEAMT in plants and whether it serves to prevent the accumulation of PtdMEA to potentially deleterious levels.
- Subjects :
- Phosphatidylethanolamine N-Methyltransferase
Saccharomyces cerevisiae
Mutant
Arabidopsis
Plant Biology
Biochemistry
Choline
chemistry.chemical_compound
Molecular Biology
Phospholipids
Phosphocholine
chemistry.chemical_classification
biology
Arabidopsis Proteins
Phosphatidylethanolamines
Genetic Complementation Test
Wild type
food and beverages
Cell Biology
Plants, Genetically Modified
biology.organism_classification
Amino acid
Complementation
chemistry
Phosphatidylethanolamine N-methyltransferase
Phosphatidylcholines
Subjects
Details
- ISSN :
- 00219258
- Volume :
- 285
- Database :
- OpenAIRE
- Journal :
- Journal of Biological Chemistry
- Accession number :
- edsair.doi.dedup.....0ed0fd36cd96a9acc130aabdcf82f0e0