Arabidopsis lipid droplet-associated protein (LDAP) interacting protein (LDIP) influences lipid droplet size and neutral lipid homeostasis in both leaves and seeds
Arabidopsis lipid droplet-associated protein (LDAP) interacting protein (LDIP) influences lipid droplet size and neutral lipid homeostasis in both leaves and seeds
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DOI：
10.1111/tpj.13754
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发表时间：
2017-12-01
期刊：
影响因子：
7.2
通讯作者：
Mullen, Robert T.
中科院分区：
文献类型：
--
作者：
Pyc, Michal;Cai, Yingqi;Mullen, Robert T.
细胞质脂滴（LD）存在于所有类型的植物细胞中;它们来源于内质网，作为中性脂质的储存库，以及在脂质重塑和信号传导中发挥作用。然而，植物LD的形成，稳态维持和周转的机制，特别是在非种子组织，是相对未知的。以前，我们表明，LD相关蛋白（LDAPs）是一个家庭的植物特异性，LD表面相关的外壳蛋白，所需的适当的生物合成的LD和中性脂质在营养组织的稳态。在这里，我们筛选了酵母双杂交文库，使用拟南芥LDAP 3同种型作为“诱饵”，努力确定其他新的LD蛋白成分。其中一个候选的LDAP 3相互作用蛋白是拟南芥At 5g 16550，这是一个植物特异性蛋白的未知功能，我们称之为LDIP（LDAP-interacting protein）。使用生物化学和细胞的方法相结合，我们表明，LDIP的目标，具体到LD表面，包含一个离散的两亲性α-螺旋靶向序列，并参与同型和异型协会本身和LDAP 3，分别。LDIP T-DNA敲低和敲除突变体的分析表明，在LD丰度的减少和增加的LD大小在叶片中的变异性，伴随着总中性脂质含量的增加。在植物种子中观察到类似的表型，其显示LD增大和种子油总量增加。总的来说，这些数据确定LDIP作为一个新的球员在LD生物学调节LD的大小和细胞中性脂质稳态在叶和种子。
Cytoplasmic lipid droplets (LDs) are found in all types of plant cells; they are derived from the endoplasmic reticulum and function as a repository for neutral lipids, as well as serving in lipid remodelling and signalling. However, the mechanisms underlying the formation, steady-state maintenance and turnover of plant LDs, particularly in non-seed tissues, are relatively unknown. Previously, we showed that the LD-associated proteins (LDAPs) are a family of plant-specific, LD surface-associated coat proteins that are required for proper biogenesis of LDs and neutral lipid homeostasis in vegetative tissues. Here, we screened a yeast two-hybrid library using the Arabidopsis LDAP3 isoform as 'bait' in an effort to identify other novel LD protein constituents. One of the candidate LDAP3-interacting proteins was Arabidopsis At5g16550, which is a plant-specific protein of unknown function that we termed LDIP (LDAP-interacting protein). Using a combination of biochemical and cellular approaches, we show that LDIP targets specifically to the LD surface, contains a discrete amphipathic a-helical targeting sequence, and participates in both homotypic and heterotypic associations with itself and LDAP3, respectively. Analysis of LDIP T-DNA knockdown and knockout mutants showed a decrease in LD abundance and an increase in variability of LD size in leaves, with concomitant increases in total neutral lipid content. Similar phenotypes were observed in plant seeds, which showed enlarged LDs and increases in total amounts of seed oil. Collectively, these data identify LDIP as a new player in LD biology that modulates both LD size and cellular neutral lipid homeostasis in both leaves and seeds.