SEp22, Salmonella Dps, a Key Molecule Bearing Both Pathogenicity and Resistance to Environmental Stresses in Salmonella

Abstract

We isolated and characterized a pathogenicity-related protein in Salmonella Enteritidis (SE) from poultry farms, and designated it as SEp22, which was identified later as Salmonella Dps, a DNA-binding protein from starved cells. Expression of SEp22 was regulated by bacterial growth in Luria-Bertani (LB) medium, showing reduced expression in the logarithmic phase but increased expression from the late logarithmic to stationary phases, which was linked to the expression of σ S both in protein as well as mRNA levels. In addition, induction of SEp22 required nutritional factors in LB or casamino acids during overnight incubation in M9 minimal medium, or even through short-term exposure to H 2 O 2 for 5-15 min. Induction of SEp22 was also remarkable after sudden addition of H 2 O 2 and exposure of the bacteria to the drying protocol. The roles of SEp22 in the pathogenicity of Salmonella in mice, the survival of Salmonella exposed to H 2 O 2 , or that under dry-stress were proved not only by the difference among Salmonella clones from environmental isolates with different levels of SEp22 expression, but also by sep22-gene-depleted mutants that originated from SECl#15-1, a wild type virulent strain with high levels of SEp22. These results suggest that SEp22 is a key molecule that is responsible for pathogenesis as well as environmental stress-resistance. In this review, the diverse roles of SEp22/Dps in Salmonella are also described, suggesting the importance of this protein in the bacterial stress responses in infection and survival, as well as in the regulation of bacterial growth through aerobic metabolism. Recent progress in SEp22/Dps research at the molecular levels is also discussed.

Differential Resuscitative Effect of Pyruvate and its Analogues on VBNC (Viable But Non-Culturable) <i>Salmonella</i>

“…In consideration of the strong infectivity of Salmonella , a better understanding and appropriate risk management of environmental Salmonella are necessary to control the spread of Salmonella to foods in general. Contamination of Salmonella from the environment to food is an important matter for food safety; however, Salmonella is known to persist and survive in the environment even after exposure to such sanitizers as hydrogen peroxide (H 2 O 2 ) ( 1 ), a widely used sanitizing agent.…”

MdsABC-Mediated Pathway for Pathogenicity in Salmonella enterica Serovar Typhimurium

“…Using diagonal gel analysis, we showed that external PSPS played an important role in the ability of the macrophage-infecting bacteria to moderate oxidative damage in membrane-bound proteins with the attenuation of extracellular SODs. This mechanism is intimately linked to the defense mechanism of S. Typhimurium against phagocytosis (32). It is likely that the overexpression of MdsABC during infection of macrophages also alters the relative abundance of membrane efflux proteins which cooperate in the export of a variety of antimicrobial agents and host antimicrobial peptides (19,33,34,35).…”

Induction of Viable but Non-culturable (VBNC) State in <i>Salmonella</i> Cultured in M9 Minimal Medium Containing High Glucose

“…We previously reported that SEp22, [11][12][13][14] which is a novel pathogenicity-related factor of S. Enteritidis, and is identical to Salmonella Dps, 15) plays a very important role in the acquisition of the dry-resistance of S. Enteritidis. 16) In the course of studying the characteristics of SEp22, we happened to find that the prolonged batch culturing of SE cells in M9 minimal medium containing 0.8% glucose (a concentration twice higher than that used in the standard culture) significantly reduced their culturability.…”