Expression of multiple forms of ferredoxin NADP+ oxidoreductase in wheat leaves
Expression of multiple forms of ferredoxin NADP+ oxidoreductase in wheat leaves
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DOI：
10.1093/jxb/erm252
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发表时间：
2007-11-01
影响因子：
6.9
通讯作者：
Bowsher, C. G.
中科院分区：
文献类型：
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作者：
Gummadova, J. O.;Fletcher, G. J.;Bowsher, C. G.
在高等植物中，存在两种形式的铁氧还蛋白NADP（+）氧化还原酶（FNR），主要是NADP（+）的光还原所需的光合pFNR，以及通过利用碳水化合物氧化期间产生的NADPH的电子产生还原铁氧还蛋白的异养hFNR。本研究的目的是研究小麦叶片中存在的多种形式的FNR和FNR异构体的能力，以响应还原剂需求的变化，通过不同的表达和N-末端加工。两种形式的pFNR mRNA（pFNRI和pFNRII）的表达在一个类似的模式沿着12厘米发育的小麦初生叶，观察到的最高水平在植物中连续生长在黑暗中的硝酸盐的存在（pFNRI）或不存在（pFNRII）分别。pFNR蛋白含量从叶基部到叶尖逐渐增加。hFNR mRNA和蛋白质在硝酸盐存在下生长的植物中位于叶的基部。在没有硝酸盐的光/暗循环中生长的植物中的FNR活性主要是由于pFNR，而hFNR在硝酸盐喂养的植物中贡献显著。不同形式的FNR在满足不断变化的代谢能力和还原剂的需求沿着线性梯度的叶发育细胞的潜在作用进行了讨论。此外，替代的N-末端裂解位点的pFNR作为一种手段，铁氧化还原蛋白和这在提供一个更有效的电子流通过一个特定的途径在体内的影响之间的区别的证据被认为是。
In higher plants there are two forms of ferredoxin NADP(+) oxidoreductase (FNR), a photosynthetic pFNR primarily required for the photoreduction of NADP(+), and a heterotrophic hFNR which generates reduced ferredoxin by utilizing electrons from NADPH produced during carbohydrate oxidation. The aim of this study was to investigate the presence of multiple forms of FNR in wheat leaves and the capacity of FNR isoforms to respond to changes in reductant demand through varied expression and N-terminal processing. Two forms of pFNR mRNA (pFNRI and pFNRII) were expressed in a similar pattern along the 12 cm developing primary wheat leaf, with the highest levels observed in plants grown continuously in the dark in the presence (pFNRI) or absence (pFNRII) of nitrate respectively. pFNR protein increased from the leaf base to tip. hFNR mRNA and protein was in the basal part of the leaf in plants grown in the presence of nitrate. FNR activity in plants grown in a light/dark cycle without nitrate was mainly due to pFNR, whilst hFNR contributed significantly in nitrate-fed plants. The potential role of distinct forms of FNR in meeting the changing metabolic capacity and reductant demands along the linear gradient of developing cells of the leaf are discussed. Furthermore, evidence for alternative N-terminal cleavage sites of pFNR acting as a means of discriminating between ferredoxins and the implications of this in providing a more effective flow of electrons through a particular pathway in vivo is considered.