Physiological role of sulfite oxidase in plants

在此之前，我们已经发现了亚硫酸盐氧化酶（SO）在植物中的存在。我们克隆了它的基因，并提供了详细的生物化学知识（原子结构、光谱、反应机理、亚细胞定位）。SO的底物亚硫酸盐反应性强，对细胞有潜在危害；我们表明，SO是必不可少的解毒过量的亚硫酸盐（安全阀功能）。亚硫酸盐是在硫同化过程中内源性产生的，也可以来自外部来源，如空气污染物二氧化硫。我们还发现所有植物（草本植物、树木、谷物、苔藓）都具有高度保守的SO。因此，除了安全阀的作用外，SO还必须履行基本的代谢功能。本项目的目的是确定这一基本功能，并研究硫在硫代谢中的重要性。我们将阐明SO在还原性硫化合物分解代谢降解中的作用。我们将揭示SO是否在衰老过程中发挥作用，无论是直接参与s代谢还是通过产生H2O2。我们将提供翻译后水平上的SO调控的分子和生化细节。

Previously, we have discovered the occurrence of the enzyme sulfite oxidase (SO) in plants. We have cloned its gene and provided a detailed knowledge about its biochemistry (atomic structure, spectroscopy, reaction mechanism, subcellular localization). The substrate of SO, sulfite, is highly reactive and potentially harmful for the cell; we showed that SO is essential for detoxifying excessive amounts of sulfite (safety-valve function). Sulfite is produced endogenously during sulfur assimilation and can also derive from external sources like the air pollutant sulfur dioxide. We also established that all plants (herbaceous plants, trees, cereals, mosses) posses a highly conserved SO. Hence SO must fulfill a basic metabolic function beyond its safety-valve role. It is the aim of this project to identify this basic function and to study the importance of SO for sulfur metabolism. We will clarify the function of SO for the catabolic degradation of reduced sulfur compounds. We will unveil whether SO plays a role during senescence, either directly in S-metabolism or via its production of H2O2. And we will provide molecular and biochemical details for the assumed regulation of SO at the posttranslational level.