Tailored Phenyl Esters Inhibit ClpXP and Attenuate Staphylococcus aureus α-Hemolysin Secretion

Area of Science:

• Microbiology and Infectious Diseases
• Drug Discovery and Development
• Molecular Biology

Background:

• Multidrug-resistant bacteria pose a significant global health threat, necessitating novel antimicrobial strategies.
• Targeting bacterial virulence factors, such as serine protease ClpXP, is a promising approach to combat infections.
• Previous ClpXP inhibitors based on phenyl esters lacked sufficient stability for sustained therapeutic effects.

Purpose of the Study:

• To develop and optimize novel phenyl ester inhibitors of the ClpXP protease with improved stability and potency.
• To evaluate the efficacy of these new inhibitors in attenuating the virulence of Staphylococcus aureus.
• To assess the safety profile of the developed inhibitors regarding cytotoxicity.

Main Methods:

• Systematic chemical modification of phenyl ester ClpXP inhibitors, focusing on steric shielding and phenol leaving group tuning.
• In vitro assessment of inhibitory activity against Staphylococcus aureus ClpP peptidase and ClpXP protease.
• Evaluation of cytotoxicity in human and bacterial cell lines.
• Assessment of virulence attenuation in bacterial culture and stability in aqueous buffer.

Main Results:

• Seventeen novel phenyl ester derivatives were synthesized and evaluated.
• Two compounds, MAS-19 and MAS-30, demonstrated significant inhibition (>60% at 1 μM) of S. aureus ClpP and ClpXP.
• MAS-19 and MAS-30 exhibited low cytotoxicity against human and bacterial cells.
• These novel inhibitors markedly attenuated S. aureus virulence and showed improved stability compared to the benchmark AV170.

Conclusions:

• Optimized phenyl ester inhibitors (MAS-19, MAS-30) represent a promising new class of antimicrobials targeting bacterial virulence.
• Enhanced stability and potent inhibition of ClpXP offer a viable strategy against multidrug-resistant bacteria like S. aureus.
• These findings pave the way for developing more effective treatments against challenging bacterial infections.