From Obscurity to Opportunity: LpxH Emerges as a Promising Antibiotic Target in the Battle against Gram-Negative...

The surging crisis of multidrug-resistant Gram-negative pathogens underscores the urgent need for antibiotics with novel mechanisms of action. A promising strategy is to target previously unexploited pathways, such as lipid A biosynthesis. Lipid A functions as the membrane anchor of lipopolysaccharide and constitutes the outer monolayer of the outer membrane of Gram-negative bacteria. LpxH, a Mn²⁺-dependent phosphoesterase, catalyzes the conversion of UDP-2,3-diacylglucosamine to lipid X, a key precursor in lipid A production. Disruption of this essential step compromises outer membrane integrity, leading to bacterial death, making LpxH an attractive antibiotic target. Since AstraZeneca's discovery of the first small-molecule LpxH inhibitor a decade ago, research has progressed substantially. The development of nonradioactive LpxH activity assays has enabled rapid screening and characterization of inhibitors. Structural and biochemical studies have revealed the architecture of LpxH and dynamic properties of the bound inhibitors, informing structure- and dynamics-based inhibitor design. Notably, recent breakthroughs from academic institutions and pharmaceutical companies have produced LpxH inhibitors with potent antibacterial activity against wild-type Enterobacterales in both in vitro and in vivo models. This review describes the biological role of LpxH and its paralogs, highlights recent advances in assay development and structural analysis, and surveys the current landscape of LpxH-targeting compounds in preclinical development. These collective advances establish LpxH as a novel target in the battle against multidrug-resistant Gram-negative infections and highlight a promising therapeutic opportunity that could reinvigorate the antibiotic pipeline.