Iron is an essential, but elusive element for most cells, and high affinity transport systems are usually required for its acquisition. The long range goals of this project are to characterize the regulation of the iron acquisition systems and other iron regulated genes of the enteric bacterial genus, Shigella. These studies will include (1) characterizing the mechanisms of regulation of enterobactin expression in Shigella flexneri, (2) measuring the expression of iron-regulated genes in an in vivo system, and (3) characterizing the positive and negative regulatory elements which affect expression of the gene for Congo red/heme binding (crb). Experimental approaches will utilize genetic and biochemical techniques. In vivo expression of the genes will be investigated using fusions to reporter genes, such as lux, whose expression can be readily monitored, and an in vivo labeling system has been developed to compare proteins synthesized by bacteria inside host cells to those observed in vitro. Characterization of mutants with altered gene regulation is also proposed. These studies will help define mechanisms of gene regulation both in vivo and in vitro.
