Temperature Responses of C4 Photosynthesis: Biochemical Analysis of Rubisco, Phosphoenolpyruvate Carboxylase, and Carbonic Anhydrase in Setaria viridis
Temperature Responses of C4 Photosynthesis: Biochemical Analysis of Rubisco, Phosphoenolpyruvate Carboxylase, and Carbonic Anhydrase in Setaria viridis
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DOI：
10.1104/pp.15.00586
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发表时间：
2015-11-01
期刊：
影响因子：
7.4
通讯作者：
Cousins, Asaph B.
中科院分区：
文献类型：
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作者：
Boyd, Ryan A.;Gandin, Anthony;Cousins, Asaph B.
C-4植物的CO2光合同化可能受到Rubisco、磷酸烯醇式丙酮酸羧化酶（PEPc）和碳酸酐酶（CA）的酶促速率的限制。因此，需要这些酶的活性和动力学特性，以准确地参数化C-4叶CO2交换的生物化学模型，以响应CO2可用性和温度的变化。目前还没有发表的温度响应的Rubisco羧化和氧化动力学从C-4植物，也没有已知的测量的温度依赖性的PEPc米氏常数为它的底物HCO 3-，有很少的信息，植物CA活性的温度响应。在这里，我们使用膜入口质谱测量Rubisco羧化和氧合动力学，PEPc羧化动力学的温度响应，和CA水合反应的活性和一阶速率常数从10摄氏度到40摄氏度使用C-4植物狗尾草叶粗提取物。Rubisco，PEPc和CA动力学参数的温度依赖性。这些研究结果描述了一种新的方法PEPc动力学的调查，建议由CA施加的HCO 3限制，并显示之前测量的C-3物种和C-4植物S的Rubisco温度响应之间的相似性。绿色的
The photosynthetic assimilation of CO2 in C-4 plants is potentially limited by the enzymatic rates of Rubisco, phosphoenolpyruvate carboxylase (PEPc), and carbonic anhydrase (CA). Therefore, the activity and kinetic properties of these enzymes are needed to accurately parameterize C-4 biochemical models of leaf CO2 exchange in response to changes in CO2 availability and temperature. There are currently no published temperature responses of both Rubisco carboxylation and oxygenation kinetics from a C-4 plant, nor are there known measurements of the temperature dependency of the PEPc Michaelis-Menten constant for its substrate HCO3-, and there is little information on the temperature response of plant CA activity. Here, we used membrane inlet mass spectrometry to measure the temperature responses of Rubisco carboxylation and oxygenation kinetics, PEPc carboxylation kinetics, and the activity and first-order rate constant for the CA hydration reaction from 10 degrees C to 40 degrees C using crude leaf extracts from the C-4 plant Setaria viridis. The temperature dependencies of Rubisco, PEPc, and CA kinetic parameters are provided. These findings describe a new method for the investigation of PEPc kinetics, suggest an HCO3- limitation imposed by CA, and show similarities between the Rubisco temperature responses of previously measured C-3 species and the C-4 plant S. viridis.