Kinetics, Thermodynamics, and Structural Effects of Quinoline-2-Carboxylates, Zinc-Binding Inhibitors of New Delhi Metallo-β-lactamase-1 Re-sensitizing Multidrug-Resistant Bacteria for Carbapenems

Carbapenemresistance mediated by metallo-& beta;-lactamases (MBL)such as New Delhi metallo-& beta;-lactamase-1 (NDM-1) has become amajor factor threatening the efficacy of essential & beta;-lactamantibiotics. Starting from hit fragment dipicolinic acid (DPA), 8-hydroxy-and 8-sulfonamido-quinoline-2-carboxylic acids were developed as inhibitorsof NDM-1 with highly improved inhibitory activity and binding affinity.The most active compounds formed reversibly inactive ternary protein-inhibitorcomplexes with two zinc ions as proven by native protein mass spectrometryand bio-layer interferometry. Modification of the NDM-1 structurewith remarkable entropic gain was shown by isothermal titration calorimetryand NMR spectroscopy of isotopically labeled protein. The best compoundswere potent inhibitors of NDM-1 and other representative MBL withno or little inhibition of human zinc-binding enzymes. These inhibitorssignificantly reduced the minimum inhibitory concentrations (MIC)of meropenem for multidrug-resistant bacteria recombinantly expressing bla (NDM-1) as well as for several multidrug-resistantclinical strains at concentrations non-toxic to human cells.