Uncharacterized protein STY1099, encoded by the yccT gene, was previously identified as the most altered (i.e., upregulated) protein among the ZnO nanoparticle (NP) stimulon of Salmonella enterica serovar Enteritidis. Here we combined various stress response-related assays with functional genetics, global transcriptomic and proteomic analyses to characterize the yccT gene and its STY1099 product. Exposure of S. enterica Enteritidis to H2O2 (i.e., hydrogen peroxide) resulted in a significant (p < 0.0001) upregulation of the yccT gene, whereas exposure to paraquat (i.e., superoxide) did not alter the expression of the yccT gene. The ∆yccT mutant of S. enterica Enteritidis exposed to 0.75 mM H2O2, showed significantly reduced (p < 0.05) viability compared to the wild type strain. Further, comparative transcriptome analyses supported by Co-immunoprecipitation (Co-IP) assay revealed that STY1099 protein plays a role in redox homeostasis during the peroxide stress assault via involvement in the processes of respiratory nitrate reductase, oxidoreductase activities, cellular uptake and stress response. In addition, we found that the STY1099 protein has the monopolar subcellular location and that it interacts with key cell division proteins, MinD, and FtsH, as well as with a rod shape-determining protein MerB.
Keywords: STY1099 protein; Salmonella enterica serovar Enteritidis; cell division; nitrate reductase; peroxide stress response.