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

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• 作者：Zhisheng Zhang¹ ; ² ; Yuanyuan Xu¹ ; Zongwang Xie¹ ; Xiangyang Li¹ ; Zheng-Hui He³ ; Xin-Xiang Peng¹ ; ^{xpeng@scau.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：association&ndash ; dissociation ; catalase ; glycolate oxidase ; hydrogen peroxide ; salicylic acid
• 刊名：Molecular Plant
• 出版年：2016
• 出版时间：2 May 2016
• 年：2016
• 卷：9
• 期：5
• 页码：737-748
• 全文大小：1357 K

文摘

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 alternative source for H₂O₂ production during both gene-for-gene 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 K_m ≈ 43 mM) 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.