Phloem Proteomics Reveals New Lipid-Binding Proteins with a Putative Role in Lipid-Mediated Signaling.
Phloem Proteomics Reveals New Lipid-Binding Proteins with a Putative Role in Lipid-Mediated Signaling.
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DOI：
10.3389/fpls.2016.00563
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发表时间：
2016
影响因子：
5.6
通讯作者：
Hoffmann-Benning S
中科院分区：
文献类型：
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作者：
Barbaglia AM;Tamot B;Greve V;Hoffmann-Benning S
全球气候变化对我们为日益增长的世界人口种植所需粮食的能力产生了负面影响。为了应对未来由于非生物胁迫造成的作物损失，我们需要了解负责植物发育变化和由此产生的适应的信号，特别是通过植物韧皮部长距离传播的信号分子。利用蛋白质组学的方法，我们已经确定了几个假定的脂质结合蛋白的韧皮部分泌物。同时，我们确定了几个复杂的脂质以及茉莉酸酯。这些发现促使我们提出韧皮部（磷酸化）脂质可以作为响应非生物胁迫的长距离发育信号，并且它们被韧皮部脂质结合蛋白释放、感知和移动（Benning等人，）。事实上，我们鉴定的蛋白质包括可以将信号脂质释放到韧皮部的脂肪酶、推定的受体成分和可以介导脂质运动的蛋白质。为了测试这种可能的基于蛋白质的脂质信号传导途径，本文描述了可能在中继中起作用的三种蛋白质：（I）推定的GDSL基序脂肪酶;（II）PIG-P样蛋白，具有可能的受体样功能;（III）和PLAFP（韧皮部脂质相关家族蛋白），一种预测的功能未知的脂质结合蛋白。在这里，我们表明，所有这三种蛋白质结合脂质，特别是磷脂酸（PtdOH），这是已知的参与细胞内应激信号。编码这些蛋白质的基因在脉管系统中表达，这是韧皮部运输的先决条件。细胞定位研究表明，蛋白质不保留在内质网，但围绕细胞在一个斑点图案，已观察到以前的受体和胞间连丝蛋白。诱导PtdOH产生的非生物信号也调节GDSL-脂肪酶和PLAFP的表达，尽管是以相反的模式。我们的研究结果表明，虽然这三种蛋白质确实是脂质结合的，并在血管系统中可能在与远距离信号相关的功能中起作用，但这三种蛋白质并不以相同的方式起作用，而是以不同的途径起作用。它还指出PLAFP作为一个主要的候选人，以调查长距离脂质信号在植物干旱反应。
Global climate changes inversely affect our ability to grow the food required for an increasing world population. To combat future crop loss due to abiotic stress, we need to understand the signals responsible for changes in plant development and the resulting adaptations, especially the signaling molecules traveling long-distance through the plant phloem. Using a proteomics approach, we had identified several putative lipid-binding proteins in the phloem exudates. Simultaneously, we identified several complex lipids as well as jasmonates. These findings prompted us to propose that phloem (phospho-) lipids could act as long-distance developmental signals in response to abiotic stress, and that they are released, sensed, and moved by phloem lipid-binding proteins (Benning et al.,). Indeed, the proteins we identified include lipases that could release a signaling lipid into the phloem, putative receptor components, and proteins that could mediate lipid-movement. To test this possible protein-based lipid-signaling pathway, three of the proteins, which could potentially act in a relay, are characterized here: (I) a putative GDSL-motif lipase (II) a PIG-P-like protein, with a possible receptor-like function; (III) and PLAFP (phloem lipid-associated family protein), a predicted lipid-binding protein of unknown function. Here we show that all three proteins bind lipids, in particular phosphatidic acid (PtdOH), which is known to participate in intracellular stress signaling. Genes encoding these proteins are expressed in the vasculature, a prerequisite for phloem transport. Cellular localization studies show that the proteins are not retained in the endoplasmic reticulum but surround the cell in a spotted pattern that has been previously observed with receptors and plasmodesmatal proteins. Abiotic signals that induce the production of PtdOH also regulate the expression of GDSL-lipase and PLAFP, albeit in opposite patterns. Our findings suggest that while all three proteins are indeed lipid-binding and act in the vasculature possibly in a function related to long-distance signaling, the three proteins do not act in the same but rather in distinct pathways. It also points toward PLAFP as a prime candidate to investigate long-distance lipid signaling in the plant drought response.