Figure 2.

NDM-1 inhibition by AMA is related to both its binding affinity and selectively for Zn²⁺.A, mass spectra of AMA in its free and complexed forms. B, representative ZnPAR₂ (10 μM) absorbance in competition for Zn²⁺ with varying concentrations of AMA in 20 mM Hepes, 100 mM NaCl, and pH 7.4. The solid line represents the fit to a 1:1 Zn²⁺:AMA binding model, and dashed lines represent simulations with 10-fold higher and lower K_d values relative to the fitted mean. C, microdilution assay for the reversal of meropenem resistance in Escherichia coli producing NDM-1. AMA (cyan) or EGTA (blue) were titrated into cells in the presence of meropenem (2 μg⋅ml⁻¹) and grown overnight at 37 °C. Absorbance values at 600 nm were recorded after 18 h of incubation. Data represent mean values of two replicates ± SD. AMA, aspergillomarasmine A; NDM-1, New Delhi MBL-1; PAR, 4-(2-pyridylazo)resorcinol.