Dual regulation by phospho‐OmpR of ssrA/B gene expression in Salmonella pathogenicity island 2

• Published in: Molecular microbiology 2003-05, Vol.48 (4), p.1131-1143
• Main Authors: Feng, Xiuhong, Oropeza, Ricardo, Kenney, Linda J.
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - genetics; DNA-Binding Proteins; Gene Expression Regulation, Bacterial; Porins - physiology; Salmonella; Salmonella typhimurium - genetics; Salmonella typhimurium - growth & development; Salmonella typhimurium - pathogenicity; Trans-Activators - physiology; Transcription Factors - genetics; Transcription, Genetic
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1046/j.1365-2958.2003.03502.x

Summary Expression of genes located on Salmonella pathogenicity island 2 (SPI‐2) is required for systemic infection in mice. This region encodes a type III secretion system, secreted effectors and the two‐component regulatory system SsrA/B (also referred to as SpiR), as well as additional uncharacterized genes. In the present work, we demonstrate that phospho‐OmpR (OmpR‐P) functions as an activator at the spiC–ssrA/B locus. There are two promoters at spiR; one is upstream of ssrA and the other upstream of ssrB. Our results indicate that, in contrast to many two‐component regulatory systems, regulation of the sensor kinase SsrA appears to be uncoupled and distinct from regulation of the response regulator SsrB. OmpR regulation of ssrA/B is one of only a few examples known in which a two‐component response regulator directly regulates the expression of another two‐component regulatory system.