title: Sensitization of gram-negative bacteria by targeting the membrane potential.
abstract: Toward generating new tools for fighting multidrug-resistant (MDR) bacteria, we assessed the ability of a membrane-active peptide to sensitize gram-negative bacteria to various antibiotics. The mechanism for affecting inner and/or outer membrane functions was assessed by complementary biophysical methods (SPR, DSC, ITC). The implication of efflux pumps was examined using Acr-AB mutants, as tested with representative antibiotics, host defense peptides, and synthetic mimics. The ability to affect disease course systemically was compared for a single therapy and combination therapy, using the mouse thigh-infection model. The data show that potent antibiotic action can be provoked in vitro and in vivo, by a treatment combining two antibacterial compounds whose individual inefficiency against gram-negative bacteria stems from their efflux. Thus, at subminimal inhibitory concentrations, the lipopeptide-like sequence, N(α)(ω7)dodecenoyl-lysyl-[lysyl-aminododecanoyl-lysyl]-amide (designated C12(ω7)K-β12), has, nonetheless, rapidly achieved a transient membrane depolarization, which deprived bacteria of the proton-motive force required for active efflux. Consequently, bacteria became significantly sensitive to intracellular targeting antibiotics. Collectively, these findings suggest a potentially useful approach for expanding the antibiotics sensitivity spectrum of MDR gram-negative bacteria to include efflux substrates.
authors.affiliation: Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Keren
authors.initials: K
authors.lastname: Goldberg
authors.forename: Hadar
authors.initials: H
authors.lastname: Sarig
authors.forename: Fadia
authors.initials: F
authors.lastname: Zaknoon
authors.forename: Raquel F
authors.initials: RF
authors.lastname: Epand
authors.forename: Richard M
authors.initials: RM
authors.lastname: Epand
authors.forename: Amram
authors.initials: A
authors.lastname: Mor
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D002152:Calorimetry, Differential Scanning; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D055666:Lipopeptides / Q000737:chemistry / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects*; D051379:Mice; D008826:Microbial Sensitivity Tests; D057786:Peptidomimetics; D018892:Proton-Motive Force / Q000187:drug effects; D020349:Surface Plasmon Resonance; D013848:Thigh / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D055666:Lipopeptides; D057786:Peptidomimetics
keywords: host defense peptides; oligo-acyl-lysyl; peptidomimetics; proton motive force; synergy