Thioredoxin f1 and NADPH-Dependent Thioredoxin Reductase C Have Overlapping Functions in Regulating Photosynthetic Metabolism and Plant Growth in Response to Varying Light Conditions
Thioredoxin f1 and NADPH-Dependent Thioredoxin Reductase C Have Overlapping Functions in Regulating Photosynthetic Metabolism and Plant Growth in Response to Varying Light Conditions
复制标题
DOI：
10.1104/pp.15.01122
复制
发表时间：
2015-11-01
期刊：
影响因子：
7.4
通讯作者：
Geigenberger, Peter
中科院分区：
文献类型：
--
作者：
Thormaehlen, Ina;Meitzel, Tobias;Geigenberger, Peter
植物叶绿体中存在两种不同的硫醇氧化还原系统：铁氧还蛋白-硫氧还蛋白（Trx）系统，该系统依赖于光合电子传递链还原的铁氧还蛋白，因此依赖于光；以及NADPH依赖性Trx还原酶C（NTRC）系统，该系统依赖于NADPH，因此可能与黑暗中的糖代谢有关。因此，先前的研究表明，这两种不同的系统在植物中可能具有不同的功能。我们现在报告说，Trx f1 和 NTRC 在调节光合代谢和生长方面存在以前未被识别的功能冗余。在拟南芥 (Arabidopsis thaliana) 突变体中，Trx f1 和 NTRC 的联合缺陷（而非单一缺陷）会导致严重的生长抑制和光适应扰乱，并伴有卡尔文-本森循环活性和淀粉积累的严重损害。这些途径的关键酶——果糖-1,6-二磷酸酶和ADP-葡萄糖焦磷酸化酶——的光激活几乎完全被消除。随后 NADPH-NADP(+) 和 ATP-ADP 比率的增加导致氮同化作用增加、NADP-苹果酸脱氢酶激活以及光系统 I 核心蛋白的光脆弱性增加。在另一种方法中，记者研究表明 Trx f1 和 NTRC 蛋白共定位于相同的叶绿体亚结构中。结果提供了遗传证据，表明光和 NADPH 依赖性硫醇氧化还原系统在 Trx f1 和 NTRC 水平上相互作用，协调参与卡尔文-本森循环、淀粉代谢和响应不同光照条件的生长的调节。
Two different thiol redox systems exist in plant chloroplasts, the ferredoxin-thioredoxin (Trx) system, which depends on ferredoxin reduced by the photosynthetic electron transport chain and, thus, on light, and the NADPH-dependent Trx reductase C (NTRC) system, which relies on NADPH and thus may be linked to sugar metabolism in the dark. Previous studies suggested, therefore, that the two different systems may have different functions in plants. We now report that there is a previously unrecognized functional redundancy of Trx f1 and NTRC in regulating photosynthetic metabolism and growth. In Arabidopsis (Arabidopsis thaliana) mutants, combined, but not single, deficiencies of Trx f1 and NTRC led to severe growth inhibition and perturbed light acclimation, accompanied by strong impairments of Calvin-Benson cycle activity and starch accumulation. Light activation of key enzymes of these pathways, fructose-1,6-bisphosphatase and ADP-glucose pyrophosphorylase, was almost completely abolished. The subsequent increase in NADPH-NADP(+) and ATP-ADP ratios led to increased nitrogen assimilation, NADP-malate dehydrogenase activation, and light vulnerability of photosystem I core proteins. In an additional approach, reporter studies show that Trx f1 and NTRC proteins are both colocalized in the same chloroplast substructure. Results provide genetic evidence that light- and NADPH-dependent thiol redox systems interact at the level of Trx f1 and NTRC to coordinately participate in the regulation of the Calvin-Benson cycle, starch metabolism, and growth in response to varying light conditions.