A Vancomycin-Arginine Conjugate Inhibits Growth of Carbapenem-resistant E. coli and Targets Cell-Wall Synthesis

Abstract

<p class="first" id="P1">The emergence of multidrug-resistant Gram-negative bacteria, including carbapenem-resistant <i>Enterobacteriaceae</i>, is a major health problem that necessitates the development of new antibiotics. Vancomycin inhibits cell-wall synthesis in Gram-positive bacteria, but is generally ineffective against Gram-negative bacteria and unable to penetrate the outer membrane barrier. In an effort to determine whether vancomycin and other antibiotics effective against Gram-positive bacteria could, through modification, be rendered effective against Gram-negative bacteria, we discovered that covalent attachment of a single arginine to vancomycin yielded conjugates with order-of-magnitude improvements in activity against Gram-negative bacteria, including pathogenic <i>E. coli</i>. The vancomycin-arginine conjugate (V-R) exhibited efficacy against actively-growing bacteria, induced loss of rod cellular morphology, and resulted in intracellular accumulation of peptidoglycan precursors, all consistent with cell-wall synthesis disruption as its mechanism of action. Membrane permeabilization studies demonstrated enhanced outer membrane permeability of V-R as compared to vancomycin. The conjugate exhibited no mammalian cell toxicity or hemolytic activity in MTT and hemolysis assays. Our study introduces a new vancomycin derivative effective against Gram-negative bacteria and underscores the broader potential of generating new antibiotics through combined mode-of-action and synthesis-informed design studies. </p><p id="P2"> <div class="figure-container so-text-align-c"> <img alt="" class="figure" src="/document_file/dfa0d61e-7ed4-49c2-92de-ef63798c568f/PubMedCentral/image/nihms-1052770-f0004.jpg"/> </div> </p>