Glycolate oxidase isozymes are coordinately controlled by GLO1 and GLO4 in rice.
Glycolate oxidase isozymes are coordinately controlled by GLO1 and GLO4 in rice.
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DOI：
10.1371/journal.pone.0039658
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Peng X
中科院分区：
文献类型：
--
作者：
Zhang Z;Lu Y;Zhai L;Deng R;Jiang J;Li Y;He Z;Peng X
乙醇酸氧化酶（GLO）是光呼吸代谢的关键酶。在水稻基因组中鉴定了四个假定的GLO基因，但每个基因成员如何参与GLO活性，特别是其同工酶谱，尚不清楚。在这项研究中，我们分析了每个基因在酵母细胞和水稻组织中同工酶形成和酶活性中的作用。在水稻叶片中检测到5种GLO同工酶。GLO1和GLO4主要在水稻叶片中表达，GLO3和GLO5主要在根系中表达。酶学分析表明，除GLO5外，所有酵母表达的GLO成员都具有酶活性。进一步分析表明，GLO1、GLO3和GLO4之间存在相互作用，而GLO5之间没有相互作用。GLO1/GLO4在酵母中的共表达表现出与水稻叶片相同的同工酶模式。当GLO1或GLO4被沉默时，两个基因的表达同时被抑制，大部分GLO活性丧失，与此观察结果一致，在被沉默的植物中检测到很少GLO同工酶蛋白。而抑制GLO3则无明显影响。酵母中表达的GLO同工酶与水稻叶片中表达的GLO同工酶的比较分析表明，这5种同工酶中有2种是由GLO1或GLO4组成的同质低聚物，另外3种是由GLO1和GLO4组成的异质低聚物。我们目前的数据表明，GLO同工酶在水稻中受到GLO1和GLO4的协调控制，GLO同工酶的存在以及GLO分子和组成的复杂性暗示了GLO在植物中的潜在新作用。
Glycolate oxidase (GLO) is a key enzyme in photorespiratory metabolism. Four putative GLO genes were identified in the rice genome, but how each gene member contributes to GLO activities, particularly to its isozyme profile, is not well understood. In this study, we analyzed how each gene plays a role in isozyme formation and enzymatic activities in both yeast cells and rice tissues. Five GLO isozymes were detected in rice leaves. GLO1 and GLO4 are predominately expressed in rice leaves, while GLO3 and GLO5 are mainly expressed in the root. Enzymatic assays showed that all yeast-expressed GLO members except GLO5 have enzymatic activities. Further analyses suggested that GLO1, GLO3 and GLO4 interacted with each other, but no interactions were observed for GLO5. GLO1/GLO4 co-expressed in yeast exhibited the same isozyme pattern as that from rice leaves. When either GLO1 or GLO4 was silenced, expressions of both genes were simultaneously suppressed and most of the GLO activities were lost, and consistent with this observation, little GLO isozyme protein was detected in the silenced plants. In contrast, no observable effect was detected when GLO3 was suppressed. Comparative analyses between the GLO isoforms expressed in yeast and the isozymes from rice leaves indicated that two of the five isozymes are homo-oligomers composed of either GLO1 or GLO4, and the other three are hetero-oligomers composed of both GLO1 and GLO4. Our current data suggest that GLO isozymes are coordinately controlled by GLO1 and GLO4 in rice, and the existence of GLO isozymes and GLO molecular and compositional complexities implicate potential novel roles for GLO in plants.
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