The premise of this project is that inhibition of siderophore A (SidA) is a logical strategy for developing novel therapeutics for the treatment of fungal infections. This premise is based on a wealth of data that comes from multiple laboratories and involves genetic and biochemical experiments. We believe that this premise provides a solid foundation for the project.We hypothesize that using advanced computational approaches for in silico screening directed at various hot-spots of SidA is an innovative and viable approach for developing small molecule inhibitors for the treatment of deadly fungal infections. Because of the conservation of siderophore biosynthesis, particularly SidA homologs, we expect our discoveries to be able to treat fungal infections in plants. Goal 1. Computationally Design SidA Inhibitors and Delineate Pharmacological FeaturesWe will apply molecular dynamics (MD) simulations, pharmacophore construction algorithms, and docking with Monte Carlo refinement to identify inhibitors of SidA. The chemical features of putative ligands will be assessed by ligand grid free energy calculations and MD simulations of SidA-inhibitor complexes will be used to propose additional chemical modifications to improve affinity.Goal 2. Validate and Characterize SidA Inhibitors We will use several validated biochemical assays to determine whether compounds identified in Goal 1 are inhibitors of SidA. We will determine IC50 and KD values and the mechanisms of inhibition. The effect of inhibitors on A. fumigatus growth under iron-limiting conditions will also be tested. We will solve the 3-dimensional structure of SidA in complex with selected inhibitor(s) as well.