Set-point control of RD21 protease activity by AtSerpin1 controls cell death in Arabidopsis
Set-point control of RD21 protease activity by AtSerpin1 controls cell death in Arabidopsis
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DOI：
10.1111/tpj.12141
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发表时间：
2013-05-01
期刊：
影响因子：
7.2
通讯作者：
Fluhr, Robert
中科院分区：
文献类型：
--
作者：
Lampl, Nardy;Alkan, Noam;Fluhr, Robert
植物的程序性细胞死亡（PCD）在防御反应中起着关键作用，并通过向细胞质释放区室化蛋白酶来促进。然而，人们对这些蛋白酶的确切身份和控制知之甚少。蛇形蛋白是一类重要的蛋白，通过不可逆的抑制作用独特地抑制蛋白酶的活性；然而，它们在植物中的作用仍然不清楚。本研究表明，在细胞死亡过程中，拟南芥丝氨酸蛋白酶抑制剂AtSerpin1通过抑制其靶促死亡蛋白酶RD21而表现出促生存功能。AtSerpin1在细胞质中积累，RD21在液泡和内质网体中积累。细胞死亡的激发子，包括水杨酸激动剂苯并噻二唑和真菌毒素草酸，通过标记染料分布的变化来测量液泡通透性的变化。同时，一个共价的AtSerpin1RD21复合体被检测到，表明蛋白酶区隔化的变化。此外，缺乏RD21的突变株或AtSerpin1过表达的突变株比缺乏AtSerpin1的突变株表现出更少的激发子刺激的PCD。坏死性真菌灰霉病菌和菌核菌分泌草酸作为一种毒素，刺激细胞死亡。与RD21蛋白酶的促死亡功能一致，在缺乏RD21的植物中，这些坏死细胞的生长受到抑制，而在缺乏AtSerpin1的植物中，生长加速。结果表明，AtSerpin1通过确定其活性的设定点和限制细胞死亡过程中诱导的损伤来控制区域化蛋白酶RD21的促死亡功能。
Programmed cell death (PCD) in plants plays a key role in defense response and is promoted by the release of compartmentalized proteases to the cytoplasm. Yet the exact identity and control of these proteases is poorly understood. Serpins are an important group of proteins that uniquely curb the activity of proteases by irreversible inhibition; however, their role in plants remains obscure. Here we show that during cell death the Arabidopsis serpin protease inhibitor, AtSerpin1, exhibits a pro-survival function by inhibiting its target pro-death protease, RD21. AtSerpin1 accumulates in the cytoplasm and RD21 accumulates in the vacuole and in endoplasmic reticulum bodies. Elicitors of cell death, including the salicylic acid agonist benzothiadiazole and the fungal toxin oxalic acid, stimulated changes in vacuole permeability as measured by the changes in the distribution of marker dye. Concomitantly, a covalent AtSerpin1RD21 complex was detected indicative of a change in protease compartmentalization. Furthermore, mutant plants lacking RD21 or plants with AtSerpin1 over-expression exhibited significantly less elicitor-stimulated PCD than plants lacking AtSerpin1. The necrotrophic fungi Botrytis cinerea and Sclerotina sclerotiorum secrete oxalic acid as a toxin that stimulates cell death. Consistent with a pro-death function for RD21 protease, the growth of these necrotrophs was compromised in plants lacking RD21 but accelerated in plants lacking AtSerpin1. The results indicate that AtSerpin1 controls the pro-death function of compartmentalized protease RD21 by determining a set-point for its activity and limiting the damage induced during cell death.