Homologous expression of lipid droplet protein-enhanced neutral lipid accumulation in the marine diatom Phaeodactylum tricornutum
Homologous expression of lipid droplet protein-enhanced neutral lipid accumulation in the marine diatom Phaeodactylum tricornutum
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DOI：
10.1007/s10811-018-1402-9
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发表时间：
2018-01
影响因子：
3.3
通讯作者：
Kohei Yoneda;Masaki Yoshida;I. Suzuki;M. Watanabe
中科院分区：
文献类型：
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作者：
Kohei Yoneda;Masaki Yoshida;I. Suzuki;M. Watanabe
脂滴是普遍存在的细胞区室，其表面储存中性脂质和特定蛋白质。这些蛋白质作为维持脂滴结构的支架或作为脂肪生成或脂肪分解的调节剂。此前，在海洋硅藻三角褐指藻中鉴定出了最丰富的脂滴蛋白，即原生藻菌型脂滴蛋白（StLDP）；然而，其功能仍不清楚，因为 StLDP 没有揭示与已知脂滴蛋白的同源性，并且缺乏可预测的结构域。在这项研究中，P.转化三角藻以在 fcpA 启动子下表达同源 StLDP 基因，以确定其功能。 StLDP 表达在突变体 (H8) 中强烈增强，尤其是在氮充足的条件下；然而，它在缺氮条件下减弱。尽管表达强烈，但在氮充足条件下，野生型 (WT) 和 H8 之间的脂质组成没有观察到显着差异。在无氮培养基中培养 6 天后，H8 中的中性脂质含量显着高于 WT。在无氮培养基中培养2天后，WT中97.0%的单细胞形成1个或2个脂滴，而在H8中，这一比例下降至78.8%，并且形成3个或4个脂滴的细胞比例增加。因此，推测 StLDP 的功能是在最初的脂滴形成中螯合三酰甘油。
Lipid droplets are ubiquitous cellular compartments that store neutral lipids and specific proteins localize on their surface. These proteins work as a scaffold in maintaining the lipid droplet structure or as regulators of lipogenesis or lipolysis. Previously, the most abundant lipid droplet protein, namely stramenopile-type lipid droplet protein (StLDP), was identified in the marine diatomPhaeodactylum tricornutum; however, its function remains unclear because StLDP does not reveal homology with known lipid droplet proteins and lacks a predictable domain. In this study,P. tricornutumwas transformed to express a homologous StLDP gene under an fcpA promoter in order to determine its function. StLDP expression was strongly enhanced in the mutant (H8), especially in nitrogen-sufficient conditions; however, it was attenuated in nitrogen-deficient conditions. Despite the strong expression, no significant difference was observed in the lipid composition between the wild type (WT) and H8 under nitrogen-sufficient conditions. After cultivation in nitrogen-free medium for 6 days, neutral lipid content significantly increased in H8 than in WT. After 2 days of cultivation in nitrogen-free medium, 97.0% of single cells in WT formed one or two lipid droplets, whereas in H8, this proportion decreased to 78.8%, and the proportion of cells forming three or four lipid droplets increased. Thus, the function of StLDP was speculated to sequester triacylglycerol on the initial lipid droplet formation.