New sulphonamide-peptide hybrid molecules as potential PBP 2a ligands and methicillin resistant Staphylococcus aureus...

Area of Science:

• Medicinal Chemistry
• Computational Chemistry
• Microbiology

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant threat due to its resistance to beta-lactam antibiotics.
• Penicillin-binding protein 2a (PbP 2a) is the primary mechanism conferring this resistance.
• Novel therapeutic strategies are urgently needed to overcome MRSA infections.

Purpose of the Study:

• To computationally design and evaluate novel sulphonamide-dipeptides as inhibitors of PbP 2a.
• To investigate the binding interactions and stability of lead compounds with PbP 2a.
• To assess the in vitro efficacy of identified compounds against MRSA strains.

Main Methods:

• Computational screening of fifty-five 'ala-ala' and 'ala-pro' sulphonamide-dipeptides against PbP 2a.
• Molecular dynamics simulations to assess binding stability and determine theoretical inhibition constants (Ki).
• Antimicrobial sensitivity testing of MRSA strains against selected compounds.

Main Results:

• Two compounds, 10i and 10n, demonstrated significant binding affinity for PbP 2a's active and allosteric sites.
• Compound 10i exhibited nM range inhibition, while 10n showed µM range inhibition.
• At 10 µg/ml, compounds 10i and 10n restored susceptibility to beta-lactam antibiotics in two MRSA isolates (S4 and S10).

Conclusions:

• Sulphonamide-dipeptides represent a promising class of compounds for targeting PbP 2a in MRSA.
• Compounds 10i and 10n provide a structural basis for further optimization to combat MRSA.
• These findings offer a potential new avenue for developing effective MRSA therapeutics.