Objectives: Metallo-b-lactamases (MBLs) are an emerging class of antimicrobial resistance enzymes that degrade
b-lactam antibiotics, including last-resort carbapenems. Infections caused by carbapenemase-producing
Enterobacteriaceae (CPE) are increasingly prevalent, but treatment options are limited. While several serinedependent
b-lactamase inhibitors are formulated with commonly prescribed b-lactams, no MBL inhibitors are
currently approved for combinatorial therapies. New compounds that target MBLs to restore carbapenem activity
against CPE are therefore urgently needed. Herein we identified and characterized novel synthetic peptide
inhibitors that bound to and inhibited NDM-1, which is an emerging b-lactam r... More
Objectives: Metallo-b-lactamases (MBLs) are an emerging class of antimicrobial resistance enzymes that degrade
b-lactam antibiotics, including last-resort carbapenems. Infections caused by carbapenemase-producing
Enterobacteriaceae (CPE) are increasingly prevalent, but treatment options are limited. While several serinedependent
b-lactamase inhibitors are formulated with commonly prescribed b-lactams, no MBL inhibitors are
currently approved for combinatorial therapies. New compounds that target MBLs to restore carbapenem activity
against CPE are therefore urgently needed. Herein we identified and characterized novel synthetic peptide
inhibitors that bound to and inhibited NDM-1, which is an emerging b-lactam resistance mechanism in CPE.
Methods: We leveraged Surface Localized Antimicrobial displaY (SLAY) to identify and characterize peptides that
inhibit NDM-1, which is a primary carbapenem resistance mechanism in CPE. Lead inhibitor sequences were
chemically synthesized and MBCs and MICs were calculated in the presence/absence of carbapenems. Kinetic
analysis with recombinant NDM-1 and select peptides tested direct binding and supported NDM-1 inhibitor
mechanisms of action. Inhibitors were also tested for cytotoxicity.
Results: We identified approximately 1700 sequences that potentiated carbapenem-dependent killing
against NDM-1 Escherichia coli. Several also enhanced meropenem-dependent killing of other CPE. Biochemical
characterization of a subset indicated the peptides penetrated the bacterial periplasm and directly bound NDM1
to inhibit enzymatic activity. Additionally, each demonstrated minimal haemolysis and cytotoxicity against
mammalian cell lines.
Conclusions: Our approach advances a molecular platform for antimicrobial discovery, which complements the
growing need for alternative antimicrobials. We also discovered lead NDM-1 inhibitors, which serve as a starting
point for further chemical optimization.