Oxidative stress-triggered UMPylation of SodA by YdiU modulates oxidative stress resistance in Salmonella

YdiU is a novel UMPylation modification enzyme that plays an important role in regulating chaperones, flagellar synthesis, and iron absorption in Salmonella . Here, we report that YdiU plays an important role in regulating oxidative stress in Salmonella . The expression of ydiU was dramatically induced by hydrogen peroxide (H 2 O 2 ) 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 H 2 O 2 . Further study showed slight changes in the secondary structure of SodA under oxidative stress. Structural analysis of native protein and H 2 O 2 -treated protein showed that H 2 O 2 treatment affected the conformation of Met24. The modification site Tyr12 is near Met24, and Tyr12 exposure may facilitate UMPylation by YdiU after H 2 O 2 treatment. In addition, in vivo and in vitro experiments showed that YdiU negatively regulates SodA activity. Therefore, our results identify new biological functions of YdiU, highlight the importance of UMPylation in bacterial oxidation balance, and provide the theoretical basis to study Salmonella survival and pathogenesis.