The plastid outer membrane localized LPTD1 is important for glycerolipid remodelling under phosphate starvation
The plastid outer membrane localized LPTD1 is important for glycerolipid remodelling under phosphate starvation
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DOI：
10.1111/pce.12973
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发表时间：
2017-08-01
影响因子：
7.3
通讯作者：
Schleiff, Enrico
中科院分区：
文献类型：
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作者：
Hsueh, Yi-Ching;Ehmann, Christian;Schleiff, Enrico
植物中甘油脂的合成是在质体和内质网（ER）之间协调的。甘油脂合成的核心步骤是将磷脂酸从内质网转运至叶绿体。叶绿体外膜蛋白 TGD4 属于细菌和植物中保守的 LptD 家族，选择性结合并可能转运磷脂酸。我们描述了拟南芥中的第二种 LptD 家族蛋白（atLPTD1；At2g44640），其特征是具有蓝藻 LptD 典型氨基酸特征的桶状结构域。它在体外形成直径约9埃的阳离子选择性通道。 atLPTD1 水平在磷酸盐饥饿下被诱导。表达针对 atLPTD1 的 RNAi 构建体的植物在正常条件下显示出生长表型。在 tgd4-1 背景下表达针对 atLPTD1 的 RNAi 使植物比单个突变体对光胁迫或磷酸盐限制更敏感。此外，脂质分析表明，在磷酸盐饥饿下，RNAi突变体中的二半乳糖基二酰基甘油和磺基奎诺糖基二酰基甘油水平保持恒定，而这两种脂质在野生型中增强。根据我们的结果，我们提出了 atLPTD1 在磷酸盐饥饿下将脂质从内质网转运至叶绿体的功能，该功能与 TGD4 的功能相结合。
Glycerolipid synthesis in plants is coordinated between plastids and the endoplasmic reticulum (ER). A central step within the glycerolipid synthesis is the transport of phosphatidic acid from ER to chloroplasts. The chloroplast outer envelope protein TGD4 belongs to the LptD family conserved in bacteria and plants and selectively binds and may transport phosphatidic acid. We describe a second LptD-family protein in A. thaliana (atLPTD1; At2g44640) characterized by a barrel domain with an amino-acid signature typical for cyanobacterial LptDs. It forms a cation selective channel in vitro with a diameter of about 9 angstrom. atLPTD1 levels are induced under phosphate starvation. Plants expressing an RNAi construct against atLPTD1 show a growth phenotype under normal conditions. Expressing the RNAi against atLPTD1 in the tgd4-1 background renders the plants more sensitive to light stress or phosphate limitation than the individual mutants. Moreover, lipid analysis revealed that digalactosyldiacylglycerol and sulfoquinovosyldiacylglycerol levels remain constant in the RNAi mutants under phosphate starvation, while these two lipids are enhanced in wild-type. Based on our results, we propose a function of atLPTD1 in the transport of lipids from ER to chloroplast under phosphate starvation, which is combinatory with the function of TGD4.