Investigation and Inhibition of Siderophore Biosynthesis in Pathogenic Bacteria

Iron acquisition poses a significant challenge to bacteria in many environments, including pathogenic settings. This raises the possibility of targeting siderophore production as a novel strategy to reduce the fitness of pathogens. Many bacterial siderophores are produced by the non-ribosomal peptide synthetases (NRPSs), large modular proteins that contain multiple catalytic domains joined in a single protein. We have investigated the structural basis of catalysis of these assembly-line proteins and will present our recent insights into the features that govern the delivery of amino acid and peptide substrates to the catalytic domains. Specifically, amino acids are loaded onto the peptidyl carrier protein through the activity of an adjacent adenylation domain. Our structural studies using a mechanism-based inhibitor have demonstrated the role played by a large domain rotation in the adenylation domains that is necessary for proper catalysis. We have used these insights to guide efforts to understand the role played by the linker that joins these two domains. Secondly, we have recently investigated the biosynthetic pathway for pyoverdine biosynthesis and identified the role played by PvdQ, a fatty acid hydrolase, in pyoverdine maturation. We will describe our efforts to characterize this protein and identify inhibitors that block enzyme activity and pyoverdine production in iron limiting conditions.