title: Association-Dissociation of Glycolate Oxidase with Catalase in Rice: A Potential Switch to Modulate Intracellular H2O2 Levels.
abstract: 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 Km ≈ 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.
authors.affiliation: 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.
authors.forename: Zhisheng
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Xu
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Zongwang
authors.initials: Z
authors.lastname: Xie
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Biology, San Francisco State University, San Francisco, CA 94132, USA.
authors.forename: Zheng-Hui
authors.initials: ZH
authors.lastname: He
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China. Electronic address: xpeng@scau.edu.cn.
authors.forename: Xin-Xiang
authors.initials: XX
authors.lastname: Peng
mesh_terms: D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism*; D012275:Oryza / Q000187:drug effects / Q000378:metabolism*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D020156:Salicylic Acid / Q000494:pharmacology
chemical_list: D006861:Hydrogen Peroxide; D000429:Alcohol Oxidoreductases; C020821:glycollate oxidase; D002374:Catalase; D020156:Salicylic Acid
keywords: association–dissociation; catalase; glycolate oxidase; hydrogen peroxide; salicylic acid