Biochemical characterization of two wheat phosphoethanolamine N-methyltransferase isoforms with different sensitivities to inhibition by phosphatidic acid.

ABSTRACT: In plants the triple methylation of phosphoethanolamine to phosphocholine catalyzed by phosphoethanolamine N-methyltransferase (PEAMT) is considered a rate-limiting step in the de novo synthesis of phosphatidylcholine. Besides being a major membrane phospholipid, phosphatidylcholine can be hydrolyzed into choline and phosphatidic acid. Phosphatidic acid is widely recognized as a second messenger in stress signaling, and choline can be oxidized within the chloroplast to yield the putative osmoprotectant glycine betaine. Here we describe the cloning and biochemical characterization of a second wheat PEAMT isoform that has a four times higher specific activity than the previously described WPEAMT/TaPEAMT1 enzyme and is less sensitive to product inhibition by S-adenosyl homocysteine, but more

SUBMITTER: Jost R 

PROVIDER: S-EPMC2797268 | biostudies-literature | 2009 Nov

REPOSITORIES: biostudies-literature