Characterization of S. flexneri DegP

Shigella are Gram-negative facultative intracellular pathogens that cause bacillary dysentery. An important aspect of Shigella pathogenesis is the ability of the bacteria to invade intestinal epithelial cells, multiply within the eukaryotic cell cytoplasm, and spread to adjacent cells by the polymerization of actin. An S. flexneri degP mutant was isolated in a genetic screen for mutants that invaded Henle cells but did not form wild type plaques in Henle cell monolayers (51, 52). The purpose of this study is the characterization of an S flexneri degP mutant. DegP is essential for virulence in other bacterial pathogens, therefore the role of DegP in S. flexneri virulence was investigated. Studies with the S. flexneri degP mutant indicated that DegP may be important for several stages of Shigella infection including transit through the stomach, intercellular spread and bacterial clearance by the host immune response. In addition, due to the conserved function of DegP in bacterial extracytoplasmic stress response, investigations also were undertaken into the role of S. flexneri DegP in various environmental conditions.