Université de Lorraine, INRAE, IAM, Nancy, France.
Université de Lorraine, INRAE, IAM, Nancy, France.
J Biol Chem. 2021 Jan-Jun;296:100429. doi: 10.1016/j.jbc.2021.100429. Epub 2021 Feb 17.
The formation of a persulfide group (-SSH) on cysteine residues has gained attention as a reversible posttranslational modification contributing to protein regulation or protection. The widely distributed 3-mercaptopyruvate sulfurtransferases (MSTs) are implicated in the generation of persulfidated molecules and HS biogenesis through transfer of a sulfane sulfur atom from a suitable donor to an acceptor. Arabidopsis has two MSTs, named STR1 and STR2, but they are poorly characterized. To learn more about these enzymes, we conducted a series of biochemical experiments including a variety of possible reducing systems. Our kinetic studies, which used a combination of sulfur donors and acceptors revealed that both MSTs use 3-mercaptopyruvate efficiently as a sulfur donor while thioredoxins, glutathione, and glutaredoxins all served as high-affinity sulfane sulfur acceptors. Using the redox-sensitive GFP (roGFP2) as a model acceptor protein, we showed that the persulfide-forming MSTs catalyze roGFP2 oxidation and more generally trans-persulfidation reactions. However, a preferential interaction with the thioredoxin system and glutathione was observed in case of competition between these sulfur acceptors. Moreover, we observed that MSTs are sensitive to overoxidation but are protected from an irreversible inactivation by their persulfide intermediate and subsequent reactivation by thioredoxins or glutathione. This work provides significant insights into Arabidopsis STR1 and STR2 catalytic properties and more specifically emphasizes the interaction with cellular reducing systems for the generation of HS and glutathione persulfide and reactivation of an oxidatively modified form.
半胱氨酸残基上的过硫化物基团（-SSH）的形成作为一种可逆的翻译后修饰，对蛋白质的调节或保护具有重要作用。广泛分布的 3-巯基丙酮酸硫转移酶（MSTs）通过将硫原子从合适的供体转移到受体，参与过硫化物分子和 HS 的生物发生。拟南芥有两种 MSTs，分别命名为 STR1 和 STR2，但它们的特征描述很少。为了更多地了解这些酶，我们进行了一系列生化实验，包括各种可能的还原系统。我们的动力学研究使用了一系列硫供体和受体，结果表明，两种 MSTs 都能有效地将 3-巯基丙酮酸用作硫供体，而硫氧还蛋白、谷胱甘肽和谷氧还蛋白则作为高亲和力的硫原子受体。我们使用氧化还原敏感 GFP（roGFP2）作为模型受体蛋白，表明过硫化物形成的 MST 可以催化 roGFP2 的氧化和更普遍的反式过硫化反应。然而，在这些硫受体之间存在竞争时，观察到与硫氧还蛋白系统和谷胱甘肽的优先相互作用。此外，我们观察到 MST 对过度氧化敏感，但可以通过它们的过硫化物中间产物和随后的硫氧还蛋白或谷胱甘肽的再激活来防止不可逆失活。这项工作为拟南芥 STR1 和 STR2 的催化特性提供了重要的见解，特别是强调了与细胞还原系统的相互作用，以生成 HS 和谷胱甘肽过硫化物，并使氧化修饰形式重新激活。
