Salmonella Typhimurium U32 peptidase, YdcP, promotes bacterial survival by conferring protection against in vitro and in vivo oxidative stress

YdcP, a U32 peptidase, is characterized as a putative collagenase with a role in several bacterial infections. However, its role in the pathogenesis of Salmonella Typhimurium remains elusive. Here, we investigated the role of U32 peptidase, YdcP, in the intracellular survival of S. Typhimurium (STM). Our study revealed a novel function of YdcP in protecting wild-type Salmonella from in vitro and in vivo oxidative stress. The ydcP knockout strain showed attenuated intracellular proliferation within the murine and human macrophages. Incubation of wild-type Salmonella with H2O2 induced the transcript level expression of ydcP. Moreover, deleting ydcP increased the susceptibility of the bacteria to in vitro oxidative stress. STM Delta ydcP showed increased colocalization with the gp91(phox) subunit of the NADPH phagocytic oxidase in RAW264.7 cells. Further, we observed a reduction in the expression of bacterial anti-oxidant genes in STM Delta ydcP growing within the RAW264.7 cells. The delay in the death of BALB/c mice infected with STM Delta ydcP proved the association of ydcP with the in vivo pathogenesis of Salmonella. Finally, the attenuated growth of the ydcP mutant in wild-type C57BL/6 mice and the recovery of their growth inhibition in gp91phox-/- C57BL/6 mice endorsed the role of ydcP in protecting Salmonella from in vivo oxidative stress. Together, our study depicts a novel role of Salmonella Typhimurium YdcP, a putative U32 peptidase in rendering protection against oxidative stress.

Automated summary

This study reveals a novel role of U32 peptidase YdcP in Salmonella Typhimurium by protecting the bacteria from oxidative stress. The knockout of YdcP leads to attenuated intracellular proliferation of Salmonella and increased susceptibility to in vitro oxidative stress.