Control of sulphate assimilation and glutathione synthesis: interaction with N and C metabolism
Control of sulphate assimilation and glutathione synthesis: interaction with N and C metabolism
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DOI：
10.1093/jxb/erh203
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发表时间：
2004-08-01
影响因子：
6.9
通讯作者：
Rennenberg, H
中科院分区：
文献类型：
--
作者：
Kopriva, S;Rennenberg, H
硫酸盐同化是各种细胞过程中还原硫的重要来源，也是合成谷胱甘肽的重要途径，谷胱甘肽是植物逆境防御的主要因素。许多报告表明，硫酸盐的同化与硝酸盐和碳的同化协调得很好。人们早就知道，在硝酸盐缺乏期间，硫酸盐的同化减少，并且在缺乏硫酸盐的植物中减少硝酸盐的能力减弱。然而，直到最近才发现，硫酸盐同化的关键酶腺苷5'磷酸硫酸还原酶（APR）受碳水化合物的调节。在蔗糖或葡萄糖处理的植物中，APR活性被诱导，而在无二氧化碳空气中生长的植物中，APR活性被强烈降低。半胱氨酸的可用性是谷胱甘肽合成的关键因素，但谷氨酸和甘氨酸的充足供应也很重要。S、N和C协同同化的分子机制尚不清楚。半胱氨酸的前体o -乙酰丝氨酸被认为是调节硫酸盐同化的信号，但很可能不是N和C代谢的输出信号。cDNA阵列揭示了s -饥饿诱导生长素合成的相关基因，指出植物激素可能在其中起作用。显然，尽管在理解硫酸盐同化和谷胱甘肽合成的调控方面取得了重大进展，它们与N和C代谢的协调已经实现，并且确定了几个潜在的信号分子，但目前的知识仍然远远不够。
Sulphate assimilation is an essential pathway being a source of reduced sulphur for various cellular processes and for the synthesis of glutathione, a major factor in plant stress defence. Many reports have shown that sulphate assimilation is well co-ordinated with the assimilation of nitrate and carbon. It has long been known that, during nitrate deficiency, sulphate assimilation is reduced and that the capacity to reduce nitrate is diminished in plants starved for sulphate. Only recently, however, was it shown that adenosine 5' phosphosulphate reductase (APR), the key enzyme of sulphate assimilation, is regulated by carbohydrates. In plants treated with sucrose or glucose APR was induced, whereas the activity was strongly reduced in plants grown in CO2-free air. The availability of cysteine is a crucial factor in glutathione synthesis, but an adequate supply of glutamate and glycine are also important. The molecular mechanisms for the coordination of S, N, and C assimilation are not known. O-acetylserine, a precursor of cysteine, was proposed to be the signal regulating sulphate assimilation, but most probably is not the outgoing signal to N and C metabolism. cDNA arrays revealed the induction of genes involved in auxin synthesis upon S-starvation, pointing to a possible role of phytohormones. Clearly, despite significant progress in understanding the regulation of sulphate assimilation and glutathione synthesis, their co-ordination with N and C metabolism achieved, and several potential signal molecules identified, present knowledge is still far from being sufficient.