Fig. 3
From: Structural basis for species-selective targeting of Hsp90 in a pathogenic fungus
Synthesis and characterization of fungal-selective Hsp90 inhibitors. a Structure of previously reported anticancer radicicol oxime KF58333. b Plot of relative Hsp90-binding affinity for compounds determined in cytosolic extracts prepared from human (HEPG2) vs fungal (SC5314) cells. The relative binding affinities for compounds were determined in cytosolic extracts prepared from human vs fungal cells by fluorescence polarization (FP) assay and are indicated as normalized EC50 values. A red box highlights the oxime derivative CMLD013075 (1) in our panel of analogs which demonstrated the greatest combination of potency and selectivity for fungal Hsp90. EC50 values were determined by variable slope 4-parameter curve fitting of triplicate determinations at each concentration tested (R2 > 0.95, all curves). All fungal values were normalized by the ratio of geldanamycin EC50s measured in human vs fungal lysate. The experiment was repeated once with quantitatively similar results. Source data for the determination of EC50 values are provided as a source data file. c Summary of R-group substitutions and scheme for the synthesis of monocillin-derived and radicicol-derived oxime analogs 1–8. d Susceptibility testing of Hsp90 inhibitor panel using a strain of S. cerevisiae engineered to express C. albicans Hsp90 as its sole source of Hsp90. Relative growth inhibition by each compound over a twofold dilution series of concentrations is displayed in heat-map format. Each colored box represents the mean of duplicate determinations. Color scale for relative growth is provided in lower right of panel, green: no inhibition to black: complete inhibition. The experiment was repeated once to confirm results. e Inhibitor sensitivity of isogenic S. cerevisiae strains engineered to express the indicated HSP90 genes as their sole source of Hsp90. Relative growth inhibition by radicicol (top) or oxime derivative CMLD013075 is displayed in the same manner and using the same color scale as in d. The experiment was repeated as an independent biological replicate to confirm results.
