Quadros Barsé Laísa, Düchting Petra, Lupilov Natalie, Bandow Julia E, Krämer Ute, Leichert Lars I
Microbial Biochemistry, Faculty of Medicine, Ruhr University Bochum, Bochum, Germany.
Molecular Genetics and Physiology of Plants, Faculty of Biology and Biotechnology, Ruhr University Bochum, Bochum, Germany.
J Biol Chem. 2025 Mar;301(3):108159. doi: 10.1016/j.jbc.2025.108159. Epub 2025 Jan 4.
Auranofin is an inhibitor of human thioredoxin reductase, clinically used in the treatment of rheumatoid arthritis. More recently, it has been shown to possess strong antibacterial activity. Despite the structural dissimilarity and the independent evolutionary origins of human thioredoxin reductase and its bacterial counterpart (TrxB), inhibition of bacterial thioredoxin reductase is often suggested to be a major factor in auranofin's antibacterial mode of action. To test this hypothesis, we attempted to determine the mechanism of inhibition of auranofin for bacterial TrxB in the presence of thioredoxin, TrxB's natural substrate. However, the data obtained in these experiments was not consistent with a specific and exclusive interaction between TrxB and auranofin. Instead, it suggested that auranofin directly interacts with the cysteine thiols in thioredoxin, TrxB's substrate. Using the fluorescent redox protein roGFP2, we showed that auranofin does indeed directly interact with cysteine pairs in proteins, forming a thiol modification that is similar to, but clearly distinct from a disulfide bond. The Au:protein stoichiometries of auranofin-treated roGFP2 and thioredoxin strongly suggest the presence of an S-Au-S bridge between two cysteines in those proteins. These S-Au adducts form independent of thioredoxin reductase at a rate that indicates their pertinence in auranofin's antibacterial mode of action.
金诺芬是一种人类硫氧还蛋白还原酶抑制剂，临床上用于治疗类风湿性关节炎。最近，已证明它具有强大的抗菌活性。尽管人类硫氧还蛋白还原酶与其细菌对应物（TrxB）在结构上不同且进化起源独立，但抑制细菌硫氧还蛋白还原酶通常被认为是金诺芬抗菌作用模式的主要因素。为了验证这一假设，我们试图在硫氧还蛋白（TrxB的天然底物）存在的情况下，确定金诺芬对细菌TrxB的抑制机制。然而，在这些实验中获得的数据与TrxB和金诺芬之间特定且排他的相互作用不一致。相反，它表明金诺芬直接与TrxB的底物硫氧还蛋白中的半胱氨酸硫醇相互作用。使用荧光氧化还原蛋白roGFP2，我们表明金诺芬确实直接与蛋白质中的半胱氨酸对相互作用，形成一种类似于但明显不同于二硫键的硫醇修饰。金诺芬处理的roGFP2和硫氧还蛋白的金：蛋白质化学计量强烈表明这些蛋白质中两个半胱氨酸之间存在S-Au-S桥。这些S-Au加合物的形成独立于硫氧还蛋白还原酶，其速率表明它们在金诺芬抗菌作用模式中的相关性。
