Isovitexin Is a Direct Inhibitor of Staphylococcus aureus Coagulase

Area of Science:

• Microbiology and Infectious Diseases
• Pharmacology and Drug Discovery
• Biochemistry

Background:

• Staphylococcus aureus (S. aureus) is a significant cause of human pneumonia, contributing to substantial illness and death.
• S. aureus coagulase (Coa) plays a crucial role in bacterial pathogenesis and persistent infections by promoting fibrin polymerization.

Purpose of the Study:

• To investigate the inhibitory effect of isovitexin, a traditional Chinese medicine component, on Staphylococcus aureus coagulase (Coa).
• To determine if isovitexin directly interacts with Coa and identify key binding residues.
• To evaluate isovitexin's potential as a therapeutic agent against S. aureus infections.

Main Methods:

• Enzyme activity assays were performed to assess the inhibition of Coa activity by isovitexin.
• Bacterial growth assays were conducted to evaluate the effect of isovitexin on S. aureus proliferation.
• Thermal shift and fluorescence quenching assays were employed to confirm direct binding between isovitexin and Coa.
• Molecular dynamics simulations and structure-activity relationship analyses were utilized to identify key amino acid residues involved in binding.

Main Results:

• Isovitexin effectively inhibited the coagulase activity of Coa.
• Isovitexin did not interfere with the growth of S. aureus.
• Evidence from thermal shift and fluorescence quenching assays demonstrated a direct binding interaction between isovitexin and Coa.
• V191 and P268 were identified as critical amino acid residues for isovitexin binding to Coa.

Conclusions:

• Isovitexin acts as a direct inhibitor of Staphylococcus aureus coagulase (Coa).
• The binding of isovitexin to Coa involves specific amino acid residues, V191 and P268.
• Isovitexin represents a promising candidate for the development of novel therapeutic strategies against S. aureus infections.