NDM-1, the ultimate promiscuous enzyme: substrate recognition and catalytic mechanism.
The specter of a return to an era in which infectious disease looms as a significant threat to human health is not just hyperbole; there are serious concerns about the widespread overuse and misuse of antibiotics contributing to increased antibiotic resistance in pathogens. The recent discovery of a new enzyme, first identified in Klebsiella pneumoniae from a patient from New Delhi and denoted as NDM-1, represents an example of extreme promiscuity: It hydrolyzes and inactivates nearly all known β-lactam-based antibiotics with startling efficiency. NDM-1 can utilize different metal cofactors and seems to exploit an alternative mechanism based on the reaction conditions. Here we report the results of a combined experimental and theoretical study that examines the substrate, metal binding, and catalytic mechanism of the enzyme. We utilize structures obtained through X-ray crystallography, biochemical assays, and numerical simulation to construct a model of the enzyme catalytic pathway. The NDM-1 enzyme interacts with the substrate solely through zinc, or other metals, bound in the active site, explaining the observed lack of specificity against a broad range of β-lactam antibiotic agents. The zinc ions also serve to activate a water molecule that hydrolyzes the β-lactam ring through a proton shuttle.
Midwest Center for Structural Genomics and Structural Biology Center, Biosciences, Argonne National Laboratory, Argonne, IL 60439, USA.
Youngchang
Y
Kim
Mark A
MA
Cunningham
Joseph
J
Mire
Christine
C
Tesar
James
J
Sacchettini
Andrzej
A
Joachimiak
D020134:Catalytic Domain; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D007711:Klebsiella pneumoniae / Q000201:enzymology; D008670:Metals / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D011789:Quantum Theory; D015032:Zinc / Q000737:chemistry; D001618:beta-Lactamases / Q000737:chemistry / Q000378:metabolism*
D008670:Metals; D001618:beta-Lactamases; C552864:beta-lactamase NDM-1; D015032:Zinc