NV716 acts as an envelope-active adjuvant that enhances antibiotic accumulation in Pseudomonas aeruginosa

Area of Science:

• Microbiology and Infectious Diseases
• Drug Discovery and Development
• Membrane Biophysics

Background:

• Gram-negative bacterial infections pose significant treatment challenges due to limited drug penetration and robust efflux mechanisms.
• Pseudomonas aeruginosa exhibits high intrinsic resistance, necessitating novel therapeutic strategies.
• Antibiotic adjuvants offer a promising approach to overcome existing resistance mechanisms.

Purpose of the Study:

• To elucidate the mechanism of action of the polyaminoisoprenyl antibiotic adjuvant NV716 in Gram-negative bacteria.
• To quantify the relationship between NV716-induced outer membrane perturbation and intracellular antibiotic accumulation.
• To assess the potentiating effect of NV716 on antibiotic efficacy, particularly against Pseudomonas aeruginosa.

Main Methods:

• Utilized P. aeruginosa and Escherichia coli strains, including efflux-deficient and porin-mutant variants.
• Employed population-scale assays to measure outer membrane vesicle (OMV) release.
• Applied high-resolution imaging to visualize membrane alterations and OMV formation.
• Investigated the role of lipopolysaccharide (LPS) core structure in NV716 sensitivity.

Main Results:

• NV716 significantly increased intracellular antibiotic accumulation and potentiated selected antibiotics, notably doxycycline, in P. aeruginosa and E. coli.
• Evidence suggests NV716 perturbs outer membrane organization, enhancing antibiotic entry.
• Increased OMV release and visible membrane alterations were observed upon NV716 treatment.
• Truncation of the LPS core sensitized P. aeruginosa to NV716, indicating increased accessibility of lipid A.

Conclusions:

• NV716 acts by perturbing the Gram-negative outer membrane, facilitating increased intracellular antibiotic accumulation.
• This mechanism leads to antibiotic-class-dependent potentiation, offering a new strategy against resistant Gram-negative pathogens.
• The findings establish a quantitative link between controlled membrane disruption and enhanced antibiotic efficacy.