Phospholipase C5 (NPC5) is involved in galactolipid accumulation during phosphate limitation in leaves of Arabidopsis
Phospholipase C5 (NPC5) is involved in galactolipid accumulation during phosphate limitation in leaves of Arabidopsis
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DOI：
10.1111/j.1365-313x.2008.03582.x
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发表时间：
2008-10-01
期刊：
影响因子：
7.2
通讯作者：
Doermann, Peter
中科院分区：
文献类型：
--
作者：
Gaude, Nicole;Nakamura, Yuki;Doermann, Peter
植物膜中磷脂被半乳糖脂和硫脂取代代表了在磷酸盐限制土壤上生长的重要适应过程。基因表达和脂质分析表明，之前已证明可调节磷酸盐反应的 MYB 转录因子 PHR1 并不是控制膜脂质变化的主要因素。根据磷酸盐剥夺期间表达的诱导来选择磷脂降解的候选基因。相应拟南芥突变体中的脂质测量表明，在叶片磷酸盐限制期间，非特异性磷脂酶 C5 (NPC5) 是二半乳糖二酰基甘油 (DGDG) 正常积累所必需的。与亲本系相比，双突变体 npc5 pho1（介于 npc5 和磷酸盐缺陷型 pho1 突变体之间）的生长和 DGDG 含量降低。与野生型中的 28 mol% 相比，npc5 中 DGDG 的量从大约 15 mol% 增加到 22 mol%，这表明 NPC5 负责叶子中磷酸盐限制期间合成的 DGDG 的大约 50%。在大肠杆菌中的表达表明 NPC5 对磷脂酰胆碱和磷脂酰乙醇胺表现出磷脂酶 C 活性。生成了 npc5 和 pld zeta 2 的双突变体（携带磷脂酶 D zeta 2 基因突变）。 npc5 pld zeta 2 中的脂质测量表明PLD zeta 2 对叶片中DGDG 生产的贡献可以忽略不计。与半乳糖脂合成酶的叶绿体包膜定位相反，NPC5 定位于细胞质，这表明在磷酸盐限制期间，可溶性 NPC5 与膜结合，有助于磷脂转化为二酰基甘油（半乳糖脂合成的底物）。
The replacement of phospholipids by galacto- and sulfolipids in plant membranes represents an important adaptive process for growth on phosphate-limiting soils. Gene expression and lipid analyses revealed that the MYB transcription factor PHR1 that has been previously shown to regulate phosphate responses is not a major factor controlling membrane lipid changes. Candidate genes for phospholipid degradation were selected based on induction of expression during phosphate deprivation. Lipid measurements in the corresponding Arabidopsis mutants revealed that the non-specific phospholipase C5 (NPC5) is required for normal accumulation of digalactosyldiacylglycerol (DGDG) during phosphate limitation in leaves. The growth and DGDG content of a double mutant npc5 pho1 (between npc5 and the phosphate-deficient pho1 mutant) are reduced compared to parental lines. The amount of DGDG increases from approximately 15 mol% to 22 mol% in npc5, compared to 28 mol% in wild-type, indicating that NPC5 is responsible for approximately 50% of the DGDG synthesized during phosphate limitation in leaves. Expression in Escherichia coli revealed that NPC5 shows phospholipase C activity on phosphatidylcholine and phosphatidylethanolamine. A double mutant of npc5 and pld zeta 2 (carrying a mutation in the phospholipase D zeta 2 gene) was generated. Lipid measurements in npc5 pld zeta 2 indicated that the contribution of PLD zeta 2 to DGDG production in leaves is negligible. In contrast to the chloroplast envelope localization of galactolipid synthesis enzymes, NPC5 localizes to the cytosol, suggesting that, during phosphate limitation, soluble NPC5 associates with membranes where it contributes to the conversion of phospholipids to diacylglycerol, the substrate for galactolipid synthesis.