Variable Photosynthetic Roles of Two Leaf-type Ferredoxins in Arabidopsis, as Revealed by RNA Interference
Variable Photosynthetic Roles of Two Leaf-type Ferredoxins in Arabidopsis, as Revealed by RNA Interference
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DOI：
10.1111/j.1751-1097.2008.00411.x
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发表时间：
2008-11-01
影响因子：
3.3
通讯作者：
Hase, Toshiharu
中科院分区：
文献类型：
--
作者：
Hanke, Guy Thomas;Hase, Toshiharu
铁氧化还蛋白（Fd）是一种可溶性蛋白，它接受来自光系统I （PSI）的电子，并将它们提供给高等植物叶绿体中的基质酶。在线性电子流中，Fd主要向Fd:NADPH还原酶（FNR）提供电子，FNR生成NADPH用于卡尔文循环，但Fd也可能将电子返回到类囊体质体醌池，形成循环电子流。许多高等植物含有两种不同的光合作用Fd蛋白，但没有保守的序列差异使它们能够划分为进化群体。在C3光合模式植物拟南芥（Arabidopsis thaliana）中，存在两个这样的光合Fds，我们利用RNA干扰（RNAi）技术特异性地降低了该植物中不同Fds的转录丰度。令人惊讶的是，在两种不同的光合作用Fds的RNAi线中，叶绿素荧光测量的光合作用扰动显示出相反的趋势。线性电子流在Fd2（最丰富的Fd种）水平较低的细胞系中延迟，在某些情况下在Fd1（次要同工蛋白）水平较低的细胞系中增强。这些数据证明了Fd1和Fd2在光合电子转移中的作用至少是部分不同的，可能是在电子分配成线性和循环电子流的过程中。
Ferredoxin (Fd) is the soluble protein that accepts electrons from photosystem I (PSI) and makes them available to stromal enzymes in higher plant chloroplasts. In linear electron flow, Fd mainly donates electrons to Fd:NADPH reductase (FNR) which generates NADPH for use in the Calvin cycle, but Fd may also return electrons to the thylakoid plastoquinone pool, forming a cyclic electron flow. Many higher plants contain two different photosynthetic Fd proteins, but there are no conserved sequence differences that allow their division into evolutionary groups. In the model C3 photosynthesizing dicot, Arabidopsis thaliana, there are two such photosynthetic Fds, and we have exploited RNA interference (RNAi) techniques to specifically decrease transcript abundance of different Fds in this plant. Surprisingly, the perturbation of photosynthesis, as measured by cholorophyll fluorescence, in RNAi lines of the two different photosynthetic Fds shows opposite trends. Linear electron flow is retarded in lines with lower Fd2 (the most abundant Fd species) levels and under certain circumstances enhanced in lines with lower Fd1 (the minor isoprotein) levels. These data are evidences for at least partially differentiated roles of Fd1 and Fd2 in photosynthetic electron transfer, possibly in the partition of electrons into linear and cyclic electron flow.