Mol Plant:华南农业大学彭新湘研究组揭示过氧化氢信号发生新机制
日期：2016-02-26
DOI：http://dx.doi.org/10.1016/j.molp.2016.02.002 作者：彭新湘
2016年2月17日，国际著名学术杂志《Cell》子刊《Molecular Plant》杂志杂志在线发表华南农业大学生命科学学院、亚热带农业生物资源保护与利用国家重点实验室彭新湘研究组揭示过氧化氢信号发生新机制研究文章，论文题为“Association-dissociation of glycolate oxidase with catalase in rice: a potential switch to modulate intracellular H2O2 levels”。博士生张智胜为第一作者、彭新湘研究员为通讯作者。
H2O2是重要的信号分子，而C3植物中约70%的H2O2源于光呼吸中乙醇酸氧化酶(GLO)所催化的反应。通过多年的研究探索，张智胜等在水稻中发现了一种新的H2O2信号发生机制。当光呼吸代谢关键酶GLO和过氧化氢酶(CAT)发生互作时CAT的H2O2清除效率大幅提升，以致其内源H2O2浓度降低;而当GLO-CAT复合体受水杨酸(SA)等信号物质诱导解离时，H2O2浓度会瞬间提高(如图示)。这种受环境或信号物质诱导的开关机制所产生的H2O2波可进而诱导产生防卫反应，在植物抵抗高光、高温和干旱等非生物胁迫中起到关键作用。这也是光呼吸功能与机理研究方面的新进展。
图：过氧化氢信号发生机制
原文链接：
Association-dissociation of glycolate oxidase with catalase in rice: a potential switch to modulate intracellular H2O2 levels
原文摘要：
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 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, the SA-induced H2O2 accumulation is likely resulted from the SA-induced GLO-CAT dissociation. In the GLO-CAT complex, the GLO-mediated H2O2 production during photorespiration is very high wheras the affinity of CAT for H2O2 (measured Km ≈ 43 mM) is extraordinarily low. This unique combination can further potentiate the H2O2 increase 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.