Molecular Genetics of Sulfate Assimilation in Plants

9601146 Leustek该提案侧重于高等植物中硫酸盐还原的机制。 特别关注的是该途径的两种限速酶，APS-激酶和PAPS-还原酶。与提案一起提交的数据表明，在控制硫酸盐还原的生化反应方面取得了重大突破-这表明我们必须如何看待植物中的这种代谢反应的范式变化。 该提案的主要目标是通过对酶促反应进行深入的生物化学研究来加强初步数据。克隆的基因是可用的，编码激酶（APK 1）和还原酶（APR 1）。它们将被用于合成蛋白质，用于生物化学研究。该提案的主要部分是过表达酶和/或使用反义表达来减少植物中的酶量。 可能非常重要的一个方面是，APR 1与其细菌对应物不同，因为它具有连接的硫氧还蛋白结构域-可能表明这种酶受细胞的氧化还原状态控制。这一重要的硫酸盐代谢的新方面将进行分析。 硫酸盐还原是一种重要的植物代谢。这些反应为许多重要的植物过程提供了减少的硫，最著名的可能是含硫的必需氨基酸。有效地将硫酸盐减少到毒性较低的形式对树木也至关重要，因为硫酸盐是酸雨的主要破坏性成分。

9601146 Leustek The proposal focuses on the mechanisms of sulfate reduction in higher plants. Specifically in the focus are the two rate-limiting enzymes of this pathway, APS-kinase and PAPS-reductase. Data submitted with the proposal indicated a major breakthrough on the biochemical reactions that govern sulfate reduction - indicating a paradigmatic change in how we have to view this metabolic reaction in plants. The major goal of this proposal is to fortify the preliminary data by an in-depth biochemical study of the enzymatic reactions. Cloned genes are available, encoding the kinase (APK1) and reductase (APR1) enzymes. They will be used to synthesize proteins for biochemical investigations. A major part of the proposal is to over-express the enzymes and/ or to use antisense expression to reduce enzyme amounts in plants. One aspect which may be highly significant is that APR1 is different from its bacterial counterpart in that it has a thioredoxin domain attached - possibly indicating that this enzyme is controlled by the redox state of the cell. This significant new aspect of sulfate metabolism will be analyzed. Sulfate reduction is an important plant metabolism. The reactions provide reduced sulfur for a number of essential plant processes, best known may be sulfur-containing essential amino acids. Effectively reducing sulfate to a less toxic form is also crucial to, for example, trees because sulfate is the major damaging component of acid rain.