Phospholipase activities associated with the tonoplast from Acer pseudoplatanus cells: identification of a phospholipase A1 activity.
The study of phospholipase activities associated with the tonoplast of Acer pseudoplatanus was performed in vitro with sn-2-[14C]acylphosphatidylcholine (PC) as a substrate. The hydrolysis of radiolabelled PC into [14C]phosphatidic acid and [14C]lyso-PC demonstrated the presence of phospholipase D and A1 activities, respectively, associated with the tonoplast of Acer pseudoplatanus. The vacuolar sap did not show any significant phospholipase activity. In a second step, the properties of the phospholipase A1 activity was studied using tonoplast endogenous PC labelled in vivo with [14C]choline as a substrate. The phospholipase A1 showed an optimal activity at pH about 6-6.5, did not necessarily require divalent cations, but was stimulated by Mg2+ and particularly by Ca2+. This work presents the first evidence for the presence of phospholipases A1 in plant cells.
Tavernier
E
E
Laboratoire de Biochimie et Biologie Moleculaire, UFR Sciences et Techniques, Besançon, France.
Pugin
A
A
D002118:Calcium / Q000494:pharmacology; D002413:Cations, Divalent; D002478:Cells, Cultured; D006863:Hydrogen-Ion Concentration; D017830:Octoxynol / Q000494:pharmacology; D010739:Phospholipase D / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054466:Phospholipases A1; D014197:Trees; D014617:Vacuoles / Q000201:enzymology
D002413:Cations, Divalent; D017830:Octoxynol; D010741:Phospholipases A; D054466:Phospholipases A1; D010739:Phospholipase D; D002118:Calcium