Control of sulfur partitioning between primary and secondary metabolism
Control of sulfur partitioning between primary and secondary metabolism
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DOI：
10.1111/j.1365-313x.2010.04410.x
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发表时间：
2011-01-01
期刊：
影响因子：
7.2
通讯作者：
Kopriva, Stanislav
中科院分区：
文献类型：
--
作者：
Mugford, Sarah G.;Lee, Bok-Rye;Kopriva, Stanislav
硫是所有生物体必需的营养素.植物以无机硫酸盐的形式吸收大部分硫，在初级硫酸盐同化过程中将其还原并将其并入半胱氨酸。然而，一些硫酸盐被分配到次生代谢中以合成各种硫酸化化合物。硫酸盐活化后，硫酸盐利用的两条途径发生分支，形成5 '-磷酸硫酸腺苷（APS）。最近，我们发现，APS激酶限制了拟南芥中合成硫酸化二级化合物的活化硫酸盐的可用性。为了进一步剖析初级和次级代谢之间的硫分配的控制，我们分析了植物中使用APS作为底物的酶的活性增加或减少。APS激酶活性的降低导致硫代葡萄糖苷作为硫酸化次级代谢产物的主要类别的水平降低，并且初级还原产物硫醇的浓度增加。然而，该基因的过度表达并不影响芥子油苷的水平。APS还原酶的过度表达对硫代葡萄糖甙水平没有影响，但确实增加了巯基水平，但在缺乏这种酶的APR 2亚型的突变体中，硫代葡萄糖甙和巯基水平都没有受到影响。测量通量通过硫酸盐同化使用[35 S]硫酸盐证实了较大流量的硫初级同化时，APS激酶活性降低。因此，至少在拟南芥中，APS还原酶和APS激酶之间的相互作用对于初级和次级代谢之间的硫分配是重要的。
P>Sulfur is an essential nutrient for all organisms. Plants take up most sulfur as inorganic sulfate, reduce it and incorporate it into cysteine during primary sulfate assimilation. However, some of the sulfate is partitioned into the secondary metabolism to synthesize a variety of sulfated compounds. The two pathways of sulfate utilization branch after activation of sulfate to adenosine 5'-phosphosulfate (APS). Recently we showed that the enzyme APS kinase limits the availability of activated sulfate for the synthesis of sulfated secondary compounds in Arabidopsis. To further dissect the control of sulfur partitioning between the primary and secondary metabolism, we analysed plants in which activities of enzymes that use APS as a substrate were increased or reduced. Reduction in APS kinase activity led to reduced levels of glucosinolates as a major class of sulfated secondary metabolites and an increased concentration of thiols, products of primary reduction. However, over-expression of this gene does not affect the levels of glucosinolates. Over-expression of APS reductase had no effect on glucosinolate levels but did increase thiol levels, but neither glucosinolate nor thiol levels were affected in mutants lacking the APR2 isoform of this enzyme. Measuring the flux through sulfate assimilation using [35S]sulfate confirmed the larger flow of sulfur to primary assimilation when APS kinase activity was reduced. Thus, at least in Arabidopsis, the interplay between APS reductase and APS kinase is important for sulfur partitioning between the primary and secondary metabolism.