Association-Dissociation of Glycolate Oxidase with Catalase in Rice： A Potential Switch to Modulate Intracellular H2O2 Levels

作     者：Zhisheng Zhang Yuanyuan Xu Zongwang Xie Xiangyang Li Zheng-Hui He Xin-Xiang Peng 

作者机构：State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources South China Agricultural University Guangzhou 510642 China Department of Biotechnology College of Bioscience and Biotechnology Hunan Agricultural University Changsha 410128 China Department of Biology San Francisco State University San Francisco CA 94132 USA 

出 版 物：《Molecular Plant》 (分子植物（英文版）)

年 卷 期：2016年第9卷第5期

页      面：737-748页

核心收录：

学科分类：0710[理学-生物学] 071001[理学-植物学] 07[理学] 

基　　金：This work was supported by the National Natural Science Foundation of China (31170222  31470343  U 1201212) 

主　　题：association-dissociation catalase glycolate oxidase hydrogen peroxide salicylic acid 

摘      要：Rapid and dynamic change in hydrogen peroxide （H2O2） levels can serve as an important signal to regulate various biological processes in plants. The change is realized by tilting the balance between its production and scavenging rates, in which membrane-associated NADPH oxidases are known to play a crucial role. Functioning independently from NADPH oxidases, glycolate oxidase （GLO） was recently demonstrated as an aitemative source for H2O2 production during both germ-for-germ and non-host resistance in plants. In this study, we show that GLO physically interacts with catalase （CAT） in rice leaves, and that the interaction can be deregulated by salicylic acid （SA）. Furthermore, the GLO-mediated H2O2 accumulation is synergistically enhanced by SA. Based on the well-known mechanism of substrate channeling in enzyme complexes, SA-induced H2O2 accumulation likely results from SA-induced GLO-CAT dissociation. In the GLO-CAT complex, GLO-mediated H2O2 production during photorespiration is very high, whereas the affinity of CAT for H2O2 （measured Km ≈ 43 raM） is extraordinarily low. This unique combination can further potentiate the increase in H2O2 when GLO is dissociated from CAT. Taken together, we propose that the physical association-dissociation of GLO and CAT, in response to environmental stress or stimuli, seems to serve as a specific mechanism to modulate H2O2 levels in rice.