华中农业大学油菜团队研究揭示植物非特异性磷脂酶C4的定位机制_食品科技_食品资讯_食品伙伴罐�/title>

　　近日，华中农业大�?a href='//www.sqrdapp.com/news/tag_2263.html' class='zdbq' title='油菜相关食品资讯' target='_blank'>油菜团队不�a href='//www.sqrdapp.com/news/tag_2463.html' class='zdbq' title='美国相关食品资讯' target='_blank'>美国密苏里大学圣路易斯分�?唐纳德丹佛斯植物科学中心的最新合作研究成果发表，研究揭示了植物非特异�?a href='//www.sqrdapp.com/news/tag_3206.html' class='zdbq' title='磷脂相关食品资讯' target='_blank'>磷脂酶C4的定位机制、�/div>

　　非特异性磷脂酶C（non-specific phospholipase C，NPC）是植物特有的一类磷脂酶家族，因其对底物没有特异性而得名。拟南芥�?个NPC基因，研究表明，不同NPC在植物的生长发育和逆境响应过程中发挥着完全不同的作用，NPC功能上的差异可能由于它们的亚细胞定位不同造成的。NPC4与NPC5氨基酸序列相似性达88%，NPC4和NPC5都不存在跨膜结构域，NPC5定位于胞质中，而NPC4则定位于细胞质膜，NPC4的细胞质膜定位机制仍然未知、�/div>

　　在该研究中，研究者分析发现NPC4的C末端比NPC5多了17个氨基酸，对NPC4的C末端进行截短，发现NPC4��17定位于细胞质中，表明NPC4蛋白质C末端17氨基酸对于其细胞质膜定位是必须的。进一步分析发现不同物种NPC4的C末端序列存在一个保守的半胱氨酸（cysteine，cys）位点，对NPC4�?33位的半胱氨酸（Cys-533）进行点突变，发现NPC4C533A也定位于细胞质中，表明该位点Cys决定了其细胞质膜定位。Cys位点酰基化修饰是决定蛋白质亚细胞定位的一种重要方式，通过酰基化检测、体外酶活、质谱分析等鉴定到拟南芥NPC4的Cys-533为棕榈酸酰基化修饰。进一步分析发现，定位于细胞质膜的油菜BnaC01.NPC4�?31位的半胱氨酸也受到了棕榈酸酰化修饰、�/div>

　　为了研究NPC4的酰基化修饰是否是其水解细胞质膜脂筏中鞘脂的关键，研究者发现NPC4C533A的突变不影响其酶活，通过互补实验发现NPC4C533A无法回补npc4突变体在缺磷条件下鞘脂代谢的缺陷，这是由于NPC4C533A定位于细胞质中，无法水解细胞质膜脂筏中的鞘脂。以上结果表明，蛋白质C末端半胱氨酸的棕榈酸酰基化修饰导致NPC4定位于细胞质膜，进而决定了其在缺磷条件下参与膜脂重塑的功能、�/div>

　　【英文摘要【�/div>

　　No nspecific phospholipase C （NPC� is involved in plant growth, development and stress responses. To elucidate the mechanism by which NPCs mediate cellular functions, here we show that NPC4 is S‐acylated at the C‐terminus and the acylation determines its plasma membrane （PM� association and function. The acylation of NPC4 was detected using NPC4 isolated from Arabidopsis and reco nstituted in vitro. The C‐terminal Cys�?33 was identified as the S‐acylation residue and mutation of Cys�?33 to Ala�?33 of NPC4 （NPC4C533A� led to the loss of S‐acylation and membrane association of NPC4. Knockout of NPC4 impeded the phosphate deficiency‐induced decrease of the phosphosphingolipid glycosyl inositol phosphoryl ceramide （GIPC）， but introducing NPC4C533A to npc4�? failed to complement this defect, supporting that the non‐acylated NPC4C533A fails to hydrolyze GIPC during phosphate deprivation. Moreover, NPC4C533A failed to complement the primary root growth in npc4�? under stress. In addition, NPC4 in Brassica napus was S‐acylated and mutation of the S‐acylating cysteine residue of BnaC01.NPC4 led to the loss of S‐acylation and its membrane association. Together, our results reveal that S‐acylation of NPC4 in the C‐terminus is co nserved and required for its membrane association, phosphosphingolipid hydrolysis, and function in plant stress responses.

　　论文链接：https://doi.org/10.1111/tpj.15260