GidA expression in Salmonella is modulated under certain environmental conditions.

Glucose-inhibited division (GidA) protein is widely distributed in nature, and is highly conserved among bacteria and eukarya. In our previous study, a gidA mutant was attenuated in both in vitro and in vivo models of Salmonella infection. Furthermore, deletion of gidA resulted in a marked reduction in the expression of many virulence genes and proteins, suggesting a role for GidA in the regulation of Salmonella virulence. In this study, the effect of different environmental conditions (glucose, EDTA, and pH 5) on GidA expression in Salmonella was examined. Transcriptional analysis using real-time RT-PCR and a β-galactosidase assay, displayed no differences in gidA transcription and promoter activity in different environmental conditions. Conversely, semiquantitative Western blot analysis revealed a significant increase in the GidA expression in Salmonella when grown under different environmental conditions. Salmonella in vitro virulence assays showed an increased virulence potential in the environmental conditions correlating to the increase in GidA expression. Together, our data indicate that GidA expression is modulated under different environmental conditions which correlate to increased Salmonella in vitro virulence.