The Mobley lab has a long-standing interest in studying the mechanisms of virulence and fitness of Escherichia coli and Proteus mirabilis to understand how these uropathogens colonize, persist, and damage the urinary tract during urinary tract infection (UTI). We have previously studied various classes of virulence determinants produced by these species including fimbriae, hemolysins, proteases, and elaborate siderophores and heme-binding proteins to capture iron from the host. We have currently turned our attention to identifying and studying essential transporters required by uropathogenic E. coli (UPEC), a cause of uncomplicated UTI, and P. mirabilis, a cause of catheter-associated UTI, for growth and survival in the human urinary tract. As uropathogenic bacteria must acquire nutrients present in urine or those released by an inflamed or damaged epithelium to successfully colonize the urinary tract., we now are focusing on transport systems as critical functions for the survival of these two pathogens. It is our goal to characterize key transport systems and their substrates of our two most troublesome uropathogens. With this work, we are dedicated to identifying novel targets of antimicrobial therapy.