Characterization of ArtAB from Salmonella enterica Typhimurium DT104
Background: Salmonella enterica Typhimurium is the causative agent of significant food borne disease in the U.S. Phage type DT104 strains of this bacterium harbor an enterotoxin, called ArtAB, that has significant homology to pertussis toxin (PT) from Bordetella pertussis and cholera toxin (CT) from Vibrio cholerae. The goal of this study was to characterize the activity of ArtAB and compare it to other known AB-type enterotoxins. Methods and results: We cloned artAB from DT104 isolates and purified ArtAB using histidine-tag affinity chromatography. We assayed the ability of purified ArtAB to bind to and internalize into cultured mammalian cells. The activation or inhibition of cellular metabolism was assayed using the metabolic dye Alamar blue and Vero epithelial or DC2.4 dendritic cultured cells. We have also characterized the ability of ArtAB to stimulate the production of cytokines TNF-a, IL-12 and IL-4, as well as the cellular signaling molecule cAMP on these cells. Conclusions: ArtAB is a large AB-type protein with homology to other well-characterized enterotoxins. ArtAB is able to bind to and trigger signaling pathways on mammalian cells in vitro. These studies will better define the role of enterotoxins in Salmonella pathogenesis to prevent food borne illness.