Pierrugues O, Brutesco C, Oshiro J, Gouy M, Deveaux Y, Carman G M, Thuriaux P, Kazmaier M
CEA/Cadarache, DSV-DEVM Laboratoire de Radiobiologie Végétale, 13108 Saint Paul-lez-Durance, France.
J Biol Chem. 2001 Jun 8;276(23):20300-8. doi: 10.1074/jbc.M009726200. Epub 2001 Feb 26.
An Arabidopsis thaliana gene (AtLPP1) was isolated on the basis that it was transiently induced by ionizing radiation. The putative AtLPP1 gene product showed homology to the yeast and mammalian lipid phosphate phosphatase enzymes and possessed a phosphatase signature sequence motif. Heterologous expression and biochemical characterization of the AtLPP1 gene in yeast showed that it encoded an enzyme (AtLpp1p) that exhibited both diacylglycerol pyrophosphate phosphatase and phosphatidate phosphatase activities. Kinetic analysis indicated that diacylglycerol pyrophosphate was the preferred substrate for AtLpp1p in vitro. A second Arabidopsis gene (AtLPP2) was identified based on sequence homology to AtLPP1 that was also heterologously expressed in yeast. The AtLpp2p enzyme also utilized diacylglycerol pyrophosphate and phosphatidate but with no preference for either substrate. The AtLpp1p and AtLpp2p enzymes showed differences in their apparent affinities for diacylglycerol pyrophosphate and phosphatidate as well as other enzymological properties. Northern blot analyses showed that the AtLPP1 gene was preferentially expressed in leaves and roots, whereas the AtLPP2 gene was expressed in all tissues examined. AtLPP1, but not AtLPP2, was regulated in response to various stress conditions. The AtLPP1 gene was transiently induced by genotoxic stress (gamma ray or UV-B) and elicitor treatments with mastoparan and harpin. The regulation of the AtLPP1 gene in response to stress was consistent with the hypothesis that its encoded lipid phosphate phosphatase enzyme may attenuate the signaling functions of phosphatidate and/or diacylglycerol pyrophosphate that form in response to stress in plants.
一个拟南芥基因（AtLPP1）因其可被电离辐射瞬时诱导而被分离出来。推测的AtLPP1基因产物与酵母和哺乳动物的脂质磷酸磷酸酶具有同源性，并拥有一个磷酸酶特征序列基序。AtLPP1基因在酵母中的异源表达及生化特性表明，它编码一种酶（AtLpp1p），该酶具有二酰基甘油焦磷酸磷酸酶和磷脂酸磷酸酶活性。动力学分析表明，二酰基甘油焦磷酸是AtLpp1p在体外的首选底物。基于与AtLPP1的序列同源性鉴定出了第二个拟南芥基因（AtLPP2），该基因也在酵母中进行了异源表达。AtLpp2p酶同样利用二酰基甘油焦磷酸和磷脂酸，但对这两种底物均无偏好。AtLpp1p和AtLpp2p酶在对二酰基甘油焦磷酸和磷脂酸的表观亲和力以及其他酶学特性方面存在差异。Northern杂交分析表明，AtLPP1基因在叶和根中优先表达，而AtLPP2基因在所检测的所有组织中均有表达。AtLPP1受多种胁迫条件调控，而AtLPP2不受此调控。AtLPP1基因可被遗传毒性胁迫（γ射线或UV - B）以及用马斯托帕兰和harpin进行的激发子处理瞬时诱导。AtLPP1基因对胁迫的调控与以下假设一致，即其编码的脂质磷酸磷酸酶可能会减弱植物在胁迫响应中形成的磷脂酸和/或二酰基甘油焦磷酸的信号传导功能。
