Differences in the effect of phosphatidylinositol 4,5-bisphosphate on?the hydrolytic and transphosphatidylation activities of membrane-bound phospholipase D from poppy seedlings

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• 作者：Marek Oblozinsky ; Lydia Bezakova ; Johanna Mansfeld ; Ingo Heilmann ; Renate Ulbrich-Hofmann
• 关键词：Phospholipase D ; Phosphatidylinositol 4 ; 5-bisphosphate ; Hydrolysis ; Transphosphatidylation ; Papaver somniferum L.
• 刊名：Plant Physiology and Biochemistry
• 出版年：2013
• 出版时间：August, 2013
• 年：2013
• 卷：69
• 期：Complete
• 页码：39-42
• 全文大小：438 K

文摘

The hydrolytic activity of phospholipase D (PLD) yielding phosphatidic acid from phosphatidylcholine and other glycerophospholipids is known to be involved in many cellular processes. In contrast, it is not clear whether the competitive transphosphatidylation activity of PLD catalyzing the head group exchange of phospholipids has a natural function. In poppy seedlings (Papaver somniferum L.) where lipid metabolism and alkaloid synthesis are closely linked, five isoenzymes with different substrate and hydrolysis/transphosphatidylation selectivities have been detected hitherto. A membrane-bound PLD, found in microsomal fractions of poppy seedlings, is active at micromolar concentrations of Ca²⁺ ions and needs phosphatidylinositol 4,5-bisphosphate (PIP₂) as effector in the hydrolysis of phosphatidylcholine (PC). The optimum PIP₂ concentration at 1.2?mol % of the concentration of the substrate PC?indicates a specific activation effect. Transphosphatidylation with glycerol, ethanolamine, l-serine, or myo-inositol as acceptor alcohols is also activated by PIP₂, however, with an optimum concentration at 0.6-0.9?mol % . In contrast to hydrolysis, a basic transphosphatidylation activity occurs even in the absence of PIP₂, suggesting a different fine-tuning of the two competing reactions.