Enhancing the antibacterial efficacy of vancomycin analogues: targeting metallo-β-lactamases and cell wall biosynthesis.

Vancomycin is a crucial last-resort antibiotic for tackling Gram-positive bacterial infections. However, its potency fails against the more difficult-to-treat Gram-negative bacteria (GNB). Vancomycin derivatives have shown promise as broad-spectrum antibacterials, but are still underexplored. Toward this, we present a novel strategy wherein we substitute the sugar moiety of vancomycin with a dipicolyl amine group, yielding VanNHdipi. This novel glycopeptide enhances its efficacy against vancomycin-resistant bacteria by up to 100-fold. A comprehensive approach involving microbiological assays, biochemical analyses, proteomics, and computational studies unraveled the impact of this design on biological activity. Our investigations reveal that VanNHdipi, like vancomycin, disrupts membrane-bound steps of cell wall synthesis inducing envelope stress, while also interfering with the structural integrity of the cytoplasmic membrane, setting it apart from vancomycin. Most noteworthy is its potency against critical GNB producing metallo-β-lactamases (MBLs). VanNHdipi effectively inactivates various MBLs with IC50 in the range of 0.2-10 μM resulting in resensitization of MBL-producing bacteria to carbapenems. Molecular docking and molecular dynamics (MD) studies indicate that H-bonding interactions between the sugar moiety of the vancomycin derivative with the amino acids on the surface of NDM-1 facilitate enhanced binding affinity for the enzyme. This work expands the scope of vancomycin derivatives and offers a promising new avenue for combating antibiotic resistance.