Patent ID: 8389231

Claim:
A method of identifying compounds that interfere with mycobactin-mediated iron acquisition by mycobacteria within phagosomes of host cells, wherein interference with the mycobactin-mediated iron acquisition results from interference with one or more of: transport of apo-mycobactin across phagosome membranes into the host cytoplasm, formation of ferric mycobactin complexes in the host cytoplasm, accumulation of ferric mycobactin complexes in lipid droplets, or delivery of ferric mycobactin complexes to phagosomes from lipid droplets, the method comprising the steps of: a) exposing a first set of host cells, in the absence of a test compound, to an isolated mycobactin component selected from apo-mycobactin, ferric mycobactin complex, or a ferric mycobactin complex analog or derivative that binds to lipid droplets, under conditions that permit entry of the mycobactin component into the host cell cytoplasm, formation of ferric mycobactin complexes within the host cells, accumulation of ferric mycobactin complexes in lipid droplets and delivery of ferric mycobactin complexes to phagosomes from lipid droplets; b) exposing a second set of host cells, in the presence of the test compound, to the isolated mycobactin component of step a) under equivalent conditions as applied in step a); c) measuring in each of the first and second sets of host cells the amount of one or more of: i) mycobactin components present in the host cytoplasm; ii) ferric mycobactin complexes formed from apo-mycobactin; iii) ferric mycobactin complexes or ferric mycobactin complex analogs or derivatives associated with lipid droplets; and iv) ferric mycobactin complexes or ferric mycobactin analogs or derivatives present within phagosomes; d) comparing the measured amounts from step c) for the first and second sets of host cells; and e) identifying whether the test compound interfered with mycobactin-mediated iron acquisition, wherein a decrease in any of (i)-(iv) in the presence of the test compound, as compared with in the absence of the test compound, is indicative that the test compound interferes with mycobactin-mediated iron acquisition by mycobacteria within phagosomes of host cells.