Selective Permeabilization of Gram-Negative Bacterial Membranes Using Multivalent Peptide Constructs for Antibiotic Sensitization

Abstract

The drug-impermeable bacterial membrane in Gram-negative pathogens limits antibiotic access to intracellular drug targets. To expand our rapidly waning antibiotic arsenal, one approach is to improve the intracellular delivery of drugs with historically poor accumulation in Gram-negative bacteria. To do so, we engineered macromolecular potentiators to permeabilize the Gram-negative membrane to facilitate drug influx. Potentiators, known as WD40, were synthesized by grafting multiple copies of a cationic α-helical antimicrobial peptide, WLBU2, onto a dextran polymer scaffold. WD40 enabled drug uptake in the model pathogen P. aeruginosa , a capability that was not observed with unmodified WLBU2 peptide. WD40 was able to reduce minimum inhibitory concentrations of a drug panel by up to 3 orders of magnitude. Hydrophobic and highly three-dimensional antibiotics exhibited the greatest potentiation. Antibiotic activity was potentiated in several clinical strains and resulted in sensitization of drug-resistant strains to rifampin, a drug not previously used for Gram-negative infections.

Anionic Self‐Assembling Supramolecular Enhancers of Antimicrobial Efficacy against Gram‐Negative Bacteria

“…The development of molecular membrane interaction technologies has also led to the evolution of (typically peptide‐based) molecular innovations, [ 15 ] which selectively increase the permeability of Gram‐negative bacterial membranes toward antimicrobial agents and/or adjuvants. [ 16 ] For example, Brown and co‐workers investigated the use of SPR741, a polymyxin B analog, as an antimicrobial efficacy enhancer which exhibits minimal inherent antimicrobial activity itself.…”

“…[ 16 ] For example, Brown and co‐workers investigated the use of SPR741, a polymyxin B analog, as an antimicrobial efficacy enhancer which exhibits minimal inherent antimicrobial activity itself. [ 15c ] This is favorable as minimizing the antimicrobial activity of a therapeutic efficacy enhancer is crucial to avoid the generation of AMR. [ 17 ] The authors demonstrated that SPR741 was capable of destabilizing the outer membrane of Escherichia coli ( E. coli ), a common Gram‐negative pathogen.…”

Atomic-Resolution Structures and Mode of Action of Clinically Relevant Antimicrobial Peptides

“…As a matter of fact, Gram-negative bacteria are intrinsically more impervious to several conventional antibiotics compared to Gram-positive bacteria. A trove of frontline antibiotics e.g., vancomycin, rifampicin, erythromycin, novobiocin etc., which can kill Gram-positive bacteria are not used for the treatment of Gram-negative infections [7][8][9][10][11][12][13]. Permeability barrier of the outer membrane LPS and porins can significantly restrict entry of large scaffold antibiotics to the bacterial targets [7][8][9][10][11][12][13].…”

“…A trove of frontline antibiotics e.g., vancomycin, rifampicin, erythromycin, novobiocin etc., which can kill Gram-positive bacteria are not used for the treatment of Gram-negative infections [7][8][9][10][11][12][13]. Permeability barrier of the outer membrane LPS and porins can significantly restrict entry of large scaffold antibiotics to the bacterial targets [7][8][9][10][11][12][13]. Hence, there is an urgent need for the discovery and development of novel drugs which will be effective in the treatment of bacterial AMR particularly drug-resistant Gram-negative bacteria.…”

“…Cationic AMPs are often able to permeabilize anionic outer membrane LPS which is a necessary step as a part of the mode of action toward Gram-negative bacteria [26][27][28][29][30]. Concomitantly, AMPs can act as potentiators of conventional antibiotics to kill Gram-negative bacteria [11,[31][32][33][34]. Atomic resolution structures of some of the potent AMPs in complex with outer membrane LPS have revealed correlations with anti-bacterial activity [35][36][37][38][39][40].…”