Discovery of isokurarinone as an ATCase-engaging lead with potent activity against methicillin-resistant...

Area of Science:

• Microbiology
• Biochemistry
• Pharmacology

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant global health threat due to its resistance to existing antibiotics.
• Novel therapeutic strategies targeting essential metabolic pathways are urgently needed to combat MRSA infections.

Purpose of the Study:

• To identify and characterize novel inhibitors of aspartate transcarbamoylase (ATCase), a key enzyme in pyrimidine biosynthesis, as potential anti-MRSA agents.
• To evaluate the efficacy and mechanism of action of the identified compound, isokurarinone, against MRSA.

Main Methods:

• Structure-based virtual screening to identify potential ATCase inhibitors.
• Biochemical assays (SPR, DSF) to confirm direct binding of isokurarinone to ATCase.
• Metabolomic analysis to assess the impact on pyrimidine homeostasis and cellular functions.
• In vitro and in vivo studies to evaluate anti-MRSA activity, including effects on biofilms, virulence, and wound healing.

Main Results:

• Isokurarinone was identified as a potent inhibitor of MRSA ATCase, demonstrating direct binding and reducing enzyme activity.
• Treatment with isokurarinone disrupted pyrimidine nucleotide homeostasis, leading to impaired membrane integrity, reduced ATP levels, and increased oxidative stress.
• Isokurarinone exhibited additive effects with vancomycin, inhibited biofilm formation, and showed therapeutic benefits in a murine wound infection model, including accelerated wound closure and reduced bacterial burden.
• Initial safety assessments indicated cell-type-dependent cytotoxicity but no acute oral toxicity in mice.

Conclusions:

• Aspartate transcarbamoylase (ATCase) is a viable metabolic target for developing new anti-MRSA therapies.
• Isokurarinone is a promising lead compound with potent anti-MRSA activity, warranting further investigation for therapeutic development against challenging MRSA infections.