Inhibition of Phospholipase Dα by N-Acylethanolamines

• Published in: Plant physiology (Bethesda) 2002-08, Vol.129 (4), p.1892-1898
• Main Authors: Shea L. Austin-Brown, Chapman, Kent D.
• Format: Article
• Language: English
• Subjects: Abscisic Acid - pharmacology; Agronomy. Soil science and plant productions; Biochemical Processes and Macromolecular Structures; Biological and medical sciences; Brassica; Brassica - drug effects; Brassica - enzymology; Brassica - genetics; Brassica oleracea; Cabbages; Cell biochemistry; Cell physiology; Commelina communis; Dose-Response Relationship, Drug; E coli; Economic plant physiology; Enzymes; Escherichia coli; Escherichia coli - genetics; Ethanolamines - metabolism; Ethanolamines - pharmacology; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Guard cells; Lauric Acids - metabolism; Lauric Acids - pharmacology; Lipids; Molecular and cellular biology; Nicotiana - drug effects; Nicotiana tabacum; Nutrition. Photosynthesis. Respiration. Metabolism; Peels; Phosphatidylcholines - pharmacology; Phospholipase D - antagonists & inhibitors; Phospholipase D - metabolism; Phospholipids; Phospholipids - metabolism; Plant cells; Plant Epidermis - drug effects; Plant Leaves - drug effects; Plant physiology and development; Plants; Protein isoforms; Ricinus - drug effects; Ricinus - enzymology; Ricinus - genetics; Ricinus communis; Signal transduction; Stomata; Streptomyces chromofuscus
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.001974

N-Acylethanolamines (NAEs) are endogenous lipids in plants produced from the phospholipid precursor, N-acylphosphatidylethanolamine, by phospholipase D (PLD). Here, we show that seven types of plant NAEs differing in acyl chain length and degree of unsaturation were potent inhibitors of the well-characterized, plant-specific isoform of PLD-PLDα. It is notable that PLDα, unlike other PLD isoforms, has been shown not to catalyze the formation of NAEs from N-acylphosphatidylethanolamine. In general, inhibition of PLDα activity by NAEs increased with decreasing acyl chain length and decreasing degree of unsaturation, such that N-lauroylethanolamine and N-myristoylethanolamine were most potent with $\text{IC}_{50}\text{s}$ at submicromolar concentrations for the recombinant castor bean (Ricinus communis) PLDα expressed in Escherichia coli and for partially purified cabbage (Brassica oleracea) PLDα. NAEs did not inhibit PLD from Streptomyces chromofuscus, and exhibited only moderate, mixed effects for two other recombinant plant PLD isoforms. Consistent with the inhibitory biochemical effects on PLDα in vitro, N-lauroylethanolamine, but not lauric acid, selectively inhibited abscisic acid-induced closure of stomata in epidermal peels of tobacco (Nicotiana tabacum cv Xanthi) and Commelina communis at low micromolar concentrations. Together, these results provide a new class of biochemical inhibitors to assist in the evaluation of PLDα physiological function(s), and they suggest a novel, lipid mediator role for endogenously produced NAEs in plant cells.