Transgenic tobacco plants with improved cyanobacterial Rubisco expression but no extra assembly factors grow at near wild-type rates if provided with elevated CO2.
Transgenic tobacco plants with improved cyanobacterial Rubisco expression but no extra assembly factors grow at near wild-type rates if provided with elevated CO2.
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DOI：
10.1111/tpj.13098
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发表时间：
2016-01
期刊：
影响因子：
--
通讯作者：
Parry MA
中科院分区：
文献类型：
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作者：
Occhialini A;Lin MT;Andralojc PJ;Hanson MR;Parry MA
将蓝藻的碳浓缩机制和更快的Rubisco引入高等植物叶绿体可以通过增加CO2固定速率来提高光合性能，同时减少光呼吸造成的损失。我们以前证明，烟草植物将使用细长聚球藻Rubisco光合自养生长，虽然植物表现出相当慢的增长比野生型，需要补充CO2。由于担心维管植物组装因子可能不足以组装蓝藻Rubisco，先前的转基因植物包括蓝藻伴侣RbcX或羧基体蛋白CcmM35。在这里，我们表明，既不RbcX也不CcmM35是需要组装的活性蓝藻Rubisco。此外，通过改变Rubisco转基因上的基因调控序列，蓝藻Rubisco表达增强，转基因植物以接近野生型的生长速率生长，但仍然需要升高的CO2。我们进行了详细的动力学特性的酶产生和没有RbcX和CcmM35蓝藻蛋白。这些转基因植物表现出光合作用的特点，证实了预测的好处，具有较高的羧化速率常数在维管植物和潜在的氮利用效率，可以获得的Rubisco的非天然形式提供足够的CO2可以集中在附近的酶。
Introducing a carbon concentrating mechanism and a faster Rubisco from cyanobacteria into higher plant chloroplasts could improve photosynthetic performance by increasing the rate of CO2 fixation while decreasing losses caused by photorespiration. We previously demonstrated that tobacco plants will grow photoautotrophically using Synechococcus elongatus Rubisco, although the plants exhibited considerably slower growth than wild-type and required supplementary CO2. Because of concerns that vascular plant assembly factors might not be adequate for assembly of a cyanobacterial Rubisco, prior transgenic plants included the cyanobacterial chaperone RbcX or the carboxysomal protein CcmM35. Here we show that neither RbcX nor CcmM35 is needed for assembly of active cyanobacterial Rubisco. Furthermore, by altering the gene regulatory sequences on the Rubisco transgenes, cyanobacterial Rubisco expression was enhanced and the transgenic plants grew at near wild-type growth rates, though still requiring elevated CO2. We performed detailed kinetic characterization of the enzymes produced with and without the RbcX and CcmM35 cyanobacterial proteins. These transgenic plants exhibit photosynthetic characteristics that confirm the predicted benefits of non-native forms of Rubisco with higher carboxylation rate constants in vascular plants and the potential nitrogen use efficiency that may be gained provided that adequate CO2 can be concentrated near the enzyme.