The signal molecule lysophosphatidylcholine in Eschscholzia californica is rapidly metabolized by reacylation.
In cultured cells of California poppy (Eschscholzia californica), lysophosphatidylcholine (LPC) triggers a signal path that finally induces alkaloid biosynthesis. LPC is transiently generated by elicitor-activated phospholipase A(2) of the plasma membrane. Externally added LPC is rapidly acylated by a membrane-bound enzyme that shows the highest specific activity in the purified plasma membrane. The fatty acid incorporated into the sn-2 position of LPC is preferentially linoleic (18:2), which is the most abundant acyl component in the PC species of Eschscholzia cells, but a minor component of the pool of free fatty acids. The fatty acid at the sn-1 position of LPC is less important for substrate specificity. The capacity of LPC acylation by intact cells or isolated plasma membranes by far exceeds the rate of LPC generation by activated phospholipase A(2) and is not limited by the availability of acyl donors. Metabolites other than phosphatidylcholine (PC) were not significantly produced from labeled LPC within 20 min, indicating that lysophospholipases are not significantly contributing to the short-time metabolism of LPC. It is concluded that reacylation to PC is the dominating process in the detoxication of LPC and ensures the transient character of its steady state concentrations, even at maximum phospholipase A(2) activities.
Schwartze
Wieland
W
Fakultät Biowissenschaften, Institut für Pharmazie, Bereich Pharmazeutische Biologie und Pharmakologie, Abteilung Molekulare Zellbiologie, Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120 Halle, Germany.
Roos
Werner
W
D000215:Acylation / Q000187:drug effects; D000581:Amidohydrolases / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D031675:Eschscholzia / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005227:Fatty Acids / Q000032:analysis / Q000494:pharmacology; D008244:Lysophosphatidylcholines / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology; D013058:Mass Spectrometry; D054467:Phospholipases A2 / Q000378:metabolism; D013347:Subcellular Fractions / Q000187:drug effects / Q000201:enzymology; D013379:Substrate Specificity / Q000187:drug effects
D005227:Fatty Acids; D008244:Lysophosphatidylcholines; D054467:Phospholipases A2; D000581:Amidohydrolases; C019665:amidase