Expression Effects of a Cyclic Peptide Library on hilA in Salmonella

Salmonella Typhimurium is a gram-negative bacterium that produces a self-limiting gastroenteritis in the human small intestine upon ingestion of contaminated food or water. Salmonella contains a 40 kb region of DNA known as Salmonella Pathogenicity Island 1 (SPI-1), whose expression is controlled via multiple pathways as a result of various environmental signals. When conditions are optimal for invasion, various inducing signals cause the gene coding for the transcriptional activator HilA to turn on. This protein in turn activates the transcription of invasion genes located in SPI-1. The expressed SPI-1 proteins force targeted cells to uptake the bacteria through the manipulation of the epithelial cells cytoskeleton. In collaboration with Brad Jones at the University of Iowa, a plasmid library producing random cyclic peptides has been acquired. Some plasmids which reduce expression of a hilA::lacZY reporter in E. coli and in Salmonella Typhimurium have been identified