Sortase A Inhibitor Protein Nanoparticle Formulations Demonstrate Antibacterial Synergy When Combined with...

Area of Science:

• Nanotechnology and Drug Delivery
• Antimicrobial Resistance Research
• Biochemistry and Molecular Biology

Background:

• Sortase A (SrtA) is a key enzyme in bacterial cell wall anchoring of virulence factors, making it a viable target for anti-virulence strategies.
• Existing antimicrobial peptides (AMPs) face challenges including high cost, dose, and toxicity, necessitating innovative delivery and synergy approaches.
• Natural compounds like trans-chalcone, curcumin, quercetin, and berberine are known SrtA inhibitors but suffer from poor aqueous dispersibility.

Purpose of the Study:

• To engineer beta-lactoglobulin protein nanoparticles (PNPs) for encapsulating natural Sortase A inhibitors (SrtAIs).
• To improve the dispersibility, efficacy, and reduce the cost, dose, and toxicity of SrtAIs and antimicrobial peptides (AMPs).
• To evaluate the synergistic effects of SrtAI PNPs with AMPs against pathogenic bacteria.

Main Methods:

• Encapsulation of four natural SrtA inhibitors (trans-chalcone, curcumin, quercetin, berberine) into beta-lactoglobulin protein nanoparticles (PNPs).
• Minimum inhibitory concentration (MIC) and checkerboard synergy assays were performed against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria.
• Cell viability assays using HEK-293 cells were conducted to assess the safety profile of SrtAI PNPs and their combinations with AMPs.

Main Results:

• All SrtAI PNPs demonstrated inhibitory activity against both Gram-positive and Gram-negative bacteria.
• Trans-chalcone PNPs combined with pexiganan showed synergistic effects against all tested bacteria. Berberine PNPs exhibited synergy with pexiganan or indolicidin against S. aureus.
• SrtAI PNPs effectively inhibited SrtA activity and showed no toxicity to HEK-293 cells at effective concentrations, alone or in combination with AMPs.

Conclusions:

• Beta-lactoglobulin protein nanoparticles provide a safe and effective platform for delivering natural Sortase A inhibitors.
• Encapsulation enhances the antimicrobial properties of SrtAIs and enables synergistic potentiation with antimicrobial peptides.
• This nanoplatform strategy holds significant potential for developing novel, cost-effective treatments against multidrug-resistant bacterial infections.