美国杜克大学Zhen-Ming Pei研究组发现过氧化氢（H2O2）传感器HPCA1是拟南芥中的亮氨酸的重复受体激酶。这一研究成果于2020年2月19日发表在《自然》杂志上。

通过使用基于Ca²⁺成像的正向遗传筛选，他们在拟南芥中分离了过氧化氢诱导的Ca²⁺增加（hpca）突变体，并将HPCA1鉴定为富含亮氨酸的重复受体激酶，属于以前未鉴定的亚家族，在胞外结构域中有两个额外的半胱氨酸残基对。HPCA1位于质膜上，并通过共价修饰细胞外半胱氨酸残基被H2O2激活，从而导致HPCA1自身磷酸化。HPCA1在保卫细胞中介导H2O2诱导的Ca²⁺通道激活，是气孔关闭所必需的。他们的发现有助于确定植物对细胞外H2O2感知如何与各种外部压力和内部环境的反应相结合，并对改造适应性强的农作物有意义。

据介绍， H2O2是单细胞和多细胞生物中的主要活性氧，在外部压力和内部环境的作用下产生于胞外。H2O2通过水通道蛋白膜蛋白进入细胞，并共价修饰细胞质蛋白以调节信号传导和胞内过程。但是，细胞表面是否还存在H2O2传感器仍然未知。在植物细胞中，H2O2触发Ca²⁺离子的流入，这被认为与H2O2的感知和信号传递有关。

附：英文原文

Title: Hydrogen peroxide sensor HPCA1 is an LRR receptor kinase in Arabidopsis

Author: Feihua Wu, Yuan Chi, Zhonghao Jiang, Yuanyuan Xu, Ling Xie, Feifei Huang, Di Wan, Jun Ni, Fang Yuan, Xiaomei Wu, Yanyan Zhang, Li Wang, Rui Ye, Benjamin Byeon, Wenhua Wang, Shu Zhang, Matthew Sima, Suping Chen, Minghua Zhu, Jessica Pei, Douglas M. Johnson, Shan Zhu, Xiaoqiang Cao, Christopher Pei, Zijing Zai, Yihao Liu, Tianyi Liu, Gary B. Swift, Weiguo Zhang, Min Yu, Zhangli Hu, James N. Siedow, Xian Chen, Zhen-Ming Pei

Issue&Volume: 2020-02-19

Abstract: Hydrogen peroxide (H2O2) is a major reactive oxygen species in unicellular and multicellular organisms, and is produced extracellularly in response to external stresses and internal cues1,2,3,4. H2O2 enters cells through aquaporin membrane proteins and covalently modifies cytoplasmic proteins to regulate signalling and cellular processes. However, whether sensors for H2O2 also exist on the cell surface remains unknown. In plant cells, H2O2 triggers an influx of Ca2+ ions, which is thought to be involved in H2O2 sensing and signalling. Here, by using forward genetic screens based on Ca2+ imaging, we isolated hydrogen-peroxide-induced Ca2+ increases (hpca) mutants in Arabidopsis, and identified HPCA1 as a leucine-rich-repeat receptor kinase belonging to a previously uncharacterized subfamily that features two extra pairs of cysteine residues in the extracellular domain. HPCA1 is localized to the plasma membrane and is activated by H2O2 via covalent modification of extracellular cysteine residues, which leads to autophosphorylation of HPCA1. HPCA1 mediates H2O2-induced activation of Ca2+ channels in guard cells and is required for stomatal closure. Our findings help to identify how the perception of extracellular H2O2 is integrated with responses to various external stresses and internal cues in plants, and have implications for the design of crops with enhanced fitness.

DOI: 10.1038/s41586-020-2032-3

Source: https://www.nature.com/articles/s41586-020-2032-3