Identification and Biochemical Characterization of Pyrrolidinediones as Novel Inhibitors of the Bacterial Enzyme MurA

To develop novel antibiotics, targeting the early steps
of cell
wall peptidoglycan biosynthesis seems to be a promising strategy that
is still underutilized. MurA, the first enzyme in this pathway, is
targeted by the clinically used irreversible inhibitor fosfomycin.
However, mutations in its binding site can cause bacterial resistance.
We herein report a series of novel reversible pyrrolidinedione-based
MurA inhibitors that equally inhibit wild type (WT) MurA and the fosfomycin-resistant
MurA C115D mutant, showing an additive effect with fosfomycin for
the inhibition of WT MurA. For the most potent inhibitor 46 (IC50 = 4.5 μM), the mode of inhibition was analyzed
using native mass spectrometry and protein NMR spectroscopy. The compound
class was nontoxic against human cells and highly stable in human
S9 fraction, human plasma, and bacterial cell lysate. Taken together,
this novel compound class might be further developed toward antibiotic
drug candidates that inhibit cell wall
synthesis.