Structure of a CGI-58 motif provides the molecular basis of lipid droplet anchoring.
Structure of a CGI-58 motif provides the molecular basis of lipid droplet anchoring.
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DOI：
10.1074/jbc.m115.682203
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发表时间：
2015-10-30
期刊：
影响因子：
--
通讯作者：
Oberer M
中科院分区：
文献类型：
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作者：
Boeszoermenyi A;Nagy HM;Arthanari H;Pillip CJ;Lindermuth H;Luna RE;Wagner G;Zechner R;Zangger K;Oberer M
背景：CGI-58激活关键的细胞内脂肪酶ATGL。结果：CGI-58的N-末端脂滴（LD）结合基序结合十二烷基磷酸胆碱胶束的溶液结构。结论：LD结合基序由两个LD结合臂组成，独立地将蛋白质锚在LD上。意义：肽LD锚的结构揭示了CGI-58与LD的相互作用。储存在脂滴（LD）中的三酰甘油（TG）在称为脂解的高度调节的代谢过程中水解为游离脂肪酸，游离脂肪酸作为β-氧化的能量底物、膜脂质和信号分子的前体。比较基因鉴定-58（CGI-58）刺激脂肪甘油三酯脂肪酶（ATGL）的酶活性，所述脂肪甘油三酯脂肪酶催化TG水解为二酰基甘油和游离脂肪酸。在脂肪组织中，CGI-58和LD包被蛋白perilipin 1之间的蛋白质-蛋白质相互作用抑制CGI-58在基础条件下激活ATGL的能力。周脂蛋白1的磷酸化破坏了这些相互作用，并动员CGI-58激活ATGL。我们先前已经证明，在CGI-58的N末端（残基10-31）处的肽的去除消除CGI-58对LD的定位和CGI-58介导的ATGL的激活。在这里，我们表明，这种富含色氨酸的N-末端肽作为一个独立的LD锚，其三个色氨酸作为焦点的左（窝藏Trp 21和Trp 25）和右（窝藏Trp 29）锚臂。包含LD锚的肽的溶液状态NMR结构作为LD模拟物结合到十二烷基磷酸胆碱胶束上，揭示了左臂形成了一个简洁的疏水核，其包含Trp 21和Trp 25以及两个相邻的亮氨酸。Trp 29作为功能独立的锚臂的核心，因此，与仅在一个臂中发生的色氨酸取代相反，在两个臂中同时发生的色氨酸丙氨酸置换消除了CGI-58的定位和活性。
Background: CGI-58 activates the key intracellular lipase ATGL. Results: Solution structure of the N-terminal lipid droplet (LD)-binding motif of CGI-58 bound to dodecylphosphocholine micelles. Conclusion: The LD-binding motif acts independently to anchor proteins to LDs and consists of two LD-binding arms. Significance: The structure of the peptide LD anchor sheds light on the interaction of CGI-58 with LDs. Triacylglycerols (TGs) stored in lipid droplets (LDs) are hydrolyzed in a highly regulated metabolic process called lipolysis to free fatty acids that serve as energy substrates for β-oxidation, precursors for membrane lipids and signaling molecules. Comparative gene identification-58 (CGI-58) stimulates the enzymatic activity of adipose triglyceride lipase (ATGL), which catalyzes the hydrolysis of TGs to diacylglycerols and free fatty acids. In adipose tissue, protein-protein interactions between CGI-58 and the LD coating protein perilipin 1 restrain the ability of CGI-58 to activate ATGL under basal conditions. Phosphorylation of perilipin 1 disrupts these interactions and mobilizes CGI-58 for the activation of ATGL. We have previously demonstrated that the removal of a peptide at the N terminus (residues 10–31) of CGI-58 abrogates CGI-58 localization to LDs and CGI-58-mediated activation of ATGL. Here, we show that this tryptophan-rich N-terminal peptide serves as an independent LD anchor, with its three tryptophans serving as focal points of the left (harboring Trp21 and Trp25) and right (harboring Trp29) anchor arms. The solution state NMR structure of a peptide comprising the LD anchor bound to dodecylphosphocholine micelles as LD mimic reveals that the left arm forms a concise hydrophobic core comprising tryptophans Trp21 and Trp25 and two adjacent leucines. Trp29 serves as the core of a functionally independent anchor arm. Consequently, simultaneous tryptophan alanine permutations in both arms abolish localization and activity of CGI-58 as opposed to tryptophan substitutions that occur in only one arm.