Here we report that Salmonella enterica serovar Typhimurium pathogenicity island 4 carries a type I secretion system (siiCDF) which secretes an approximately 600-kDa protein (encoded by siiE). SiiE is surface expressed, and its production is regulated by HilA. SiiE and SiiF influence colonization in cattle and the invasion of bovine enterocytes.
SiiE is secreted by the Salmonella enterica serovar Typhimurium pathogenicity island 4-encoded secretion system and contributes to intestinal colonization in cattle.