The N-terminal region of acyl-CoA synthetase 3 is essential for both the localization on lipid droplets and the function in fatty acid uptake
The N-terminal region of acyl-CoA synthetase 3 is essential for both the localization on lipid droplets and the function in fatty acid uptake
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DOI：
10.1194/jlr.m024562
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发表时间：
2012-05-01
影响因子：
6.5
通讯作者：
Fuellekrug, Joachim
中科院分区：
文献类型：
--
作者：
Poppelreuther, Margarete;Rudolph, Berenice;Fuellekrug, Joachim
细胞质脂滴是内源性代谢产生的中性脂质的储存细胞器。酰基辅酶A合成酶家族蛋白是该生物合成途径中的必需酶，贡献活化脂肪酸。荧光显微镜显示，ACSL 3定位于内质网（ER）和LD，其分布依赖于细胞类型和脂肪酸的供应。ACSL 3的N-末端是正确靶向报告蛋白所必需和足够的，如通过亚细胞分级分离和共聚焦显微镜所证明的。ACSL 3的N-末端区域也被发现是酶活性所需的功能。选择性透化和计算机分析表明，ACSL 3呈现发夹膜拓扑结构，N-末端疏水氨基酸形成限制于ER膜的胞质小叶的两亲性螺旋。当中性脂质合成被外部添加脂肪酸刺激时，ACSL 3有效地从ER易位到新生LD。细胞脂肪酸摄取通过ACSL3.jlr的过表达而增加，并且通过ACSL3.jlr的RNA干扰而减少。总之，ACSL 3的结构组织允许从ER到新兴LD的快速和有效的移动。ACSL 3不仅用CoA使脂肪酸变性，而且还参与脂肪酸的细胞摄取，推测是间接通过代谢捕获。脂酰辅酶A合成酶ACSL 3在LD上的独特定位表明其在脂质的局部合成中具有功能。Poppelreuther，M.，B。鲁道夫角杜河Grossmann，M.贝克尔角，澳-地蒂勒河Ehehalt和J. Fullekrug。酰基-CoA合成酶3的N-末端区域对于脂滴上的定位和脂肪酸摄取功能都是必需的。J. Lipid Res. 2012. 53：888-900。
Cytosolic lipid droplets (LDs) are storage organelles for neutral lipids derived from endogenous metabolism. Acyl-CoA synthetase family proteins are essential enzymes in this biosynthetic pathway, contributing activated fatty acids. Fluorescence microscopy showed that ACSL3 is localized to the endoplasmic reticulum (ER) and LDs, with the distribution dependent on the cell type and the supply of fatty acids. The N-terminus of ACSL3 was necessary and sufficient for targeting reporter proteins correctly, as demonstrated by subcellular fractionation and confocal microscopy. The N-terminal region of ACSL3 was also found to be functionally required for the enzyme activity. Selective permeabilization and in silico analysis suggest that ACSL3 assumes a hairpin membrane topology, with the N-terminal hydrophobic amino acids forming an amphipathic helix restricted to the cytosolic leaflet of the ER membrane. ACSL3 was effectively translocated from the ER to nascent LDs when neutral lipid synthesis was stimulated by the external addition of fatty acids. Cellular fatty acid uptake was increased by overexpression and reduced by RNA interference of ACSL3.jlr In conclusion, the structural organization of ACSL3 allows the fast and efficient movement from the ER to emerging LDs. ACSL3 not only esterifies fatty acids with CoA but is also involved in the cellular uptake of fatty acids, presumably indirectly by metabolic trapping. The unique localization of the acyl-CoA synthetase ACSL3 on LDs suggests a function in the local synthesis of lipids.-Poppelreuther, M., B. Rudolph, C. Du, R. Grossmann, M. Becker, C. Thiele, R. Ehehalt, and J. Fullekrug. The N-terminal region of acyl-CoA synthetase 3 is essential for both the localization on lipid droplets and the function in fatty acid uptake. J. Lipid Res. 2012. 53: 888-900.