YdiU regulates Salmonella Oxidative Stress by UMPylation of SodA

The expression of ydiU was dramatically induced by hydrogen peroxide (H2O2) and the survivability of △ydiU was significantly stronger than that of WT under oxidative stress. Interestingly, in vitro and in vivo experiments showed that YdiU can interact with SodA and UMPylate it only in the presence of H2O2. Further study showed slight changes in the secondary structure of SodA under oxidative stress. Structural analysis of native protein and H2O2-treated protein showed that H2O2 treatment affected the conformation of Met24. The modification site Tyr12 is near Met24, and Tyr12 exposure may facilitate UMPylation by YdiU after H2O2 treatment.ydiU的表达可被过氧化氢（H₂O₂）显著诱导，ΔydiU菌株在氧化应激条件下的存活率显著高于野生型（WT）菌株。值得注意的是，体外与体内实验均证实，仅在H₂O₂存在时，YdiU才能与SodA发生相互作用并对其进行UMP修饰。进一步研究发现，氧化应激下SodA的二级结构仅发生轻微变化。对天然蛋白与经H₂O₂处理的蛋白开展结构分析后显示，H₂O₂处理会影响Met24的构象。该修饰位点Tyr12紧邻Met24，经H₂O₂处理后Tyr12的暴露或可促进YdiU对SodA的UMP修饰。