Sphingolipids with 2-hydroxy fatty acids aid in plasma membrane nanodomain organization and oxidative burst
Sphingolipids with 2-hydroxy fatty acids aid in plasma membrane nanodomain organization and oxidative burst
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DOI：
10.1093/plphys/kiac134
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发表时间：
2022-03-21
期刊：
影响因子：
7.4
通讯作者：
Nagano，Minoru
中科院分区：
文献类型：
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作者：
Ukawa，Tomomi;Banno，Fumihiko;Nagano，Minoru
植物鞘脂主要含有2-羟基脂肪酸（HFA），其合成是由2-羟基化酶（FAHs）催化的。在拟南芥（Arabidopsis thaliana）中，已鉴定出两个FAHs （FAH1和FAH2）。然而，由于缺乏完全缺失ofFAH1的拟南芥系，fah和鞘脂与hfa（2-羟基鞘脂）的功能仍然未知。在本研究中，我们使用基于CRISPR/ cas9的基因组编辑技术生成了afah1突变体（fah1c）。对ah1c、fah2和fah1chah2突变体的鞘脂分析显示，FAH1羟基化非常长链脂肪酸（VLCFAs），而fah2的底物是VLCFAs和棕榈酸。然而，在fah1chah2双突变体中，2-羟基鞘脂并没有完全丢失，这表明存在其他催化鞘脂FAs羟基化的酶。质膜（PM）分析和分子动力学模拟表明鞘脂酰基链的羟基在纳米结构域的组织中起着至关重要的作用，纳米结构域是由鞘脂和固醇在质膜中通过氢键形成的纳米级液体有序结构域。fah1chfah2突变体的PM中，26.7%的蛋白质表达水平低于野生型，包括模式识别受体（PRRs）、油菜素内酯不敏感1相关受体激酶1和几丁质激发子受体激酶1、NADPH氧化酶呼吸爆发氧化酶同源物D （RBOHD）和异源三聚体G蛋白等防御相关蛋白。此外，用病原体相关分子模式flg22和几丁质处理fah1chfa2突变体后，活性氧（ROS）爆发被抑制。这些结果表明，在模式触发免疫过程中，2-羟基鞘脂对于PM纳米结构域的组织和ROS突破RBOHD和PRRs是必需的。
Plant sphingolipids mostly possess 2-hydroxy fatty acids (HFA), the synthesis of which is catalyzed by FA 2-hydroxylases (FAHs). In Arabidopsis (Arabidopsis thaliana), two FAHs (FAH1 and FAH2) have been identified. However, the functions of FAHs and sphingolipids with HFAs (2-hydroxy sphingolipids) are still unknown because of the lack of Arabidopsis lines with the complete deletion ofFAH1. In this study, we generated aFAH1mutant (fah1c) using CRISPR/Cas9-based genome editing. Sphingolipid analysis offah1c,fah2, andfah1cfah2mutants revealed that FAH1 hydroxylates very long-chain FAs (VLCFAs), whereas the substrates of FAH2 are VLCFAs and palmitic acid. However, 2-hydroxy sphingolipids are not completely lost in thefah1cfah2double mutant, suggesting the existence of other enzymes catalyzing the hydroxylation of sphingolipid FAs. Plasma membrane (PM) analysis and molecular dynamics simulations revealed that hydroxyl groups of sphingolipid acyl chains play a crucial role in the organization of nanodomains, which are nanoscale liquid-ordered domains mainly formed by sphingolipids and sterols in the PM, through hydrogen bonds. In the PM of thefah1cfah2mutant, the expression levels of 26.7% of the proteins, including defense-related proteins such as the pattern recognition receptors (PRRs) brassinosteroid insensitive 1-associated receptor kinase 1 and chitin elicitor receptor kinase 1, NADPH oxidase respiratory burst oxidase homolog D (RBOHD), and heterotrimeric G proteins, were lower than that in the wild-type. In addition, reactive oxygen species (ROS) burst was suppressed in thefah1cfah2mutant after treatment with the pathogen-associated molecular patterns flg22 and chitin. These results indicated that 2-hydroxy sphingolipids are necessary for the organization of PM nanodomains and ROS burst through RBOHD and PRRs during pattern-triggered immunity.