New SufA Protease Inhibitors and Activity-based Probes: Design, Synthesis, and Antibacterial Activity Assessment

Area of Science:

• Biochemistry
• Microbiology
• Medicinal Chemistry

Background:

• Bacterial drug resistance necessitates novel therapeutic approaches.
• Finegoldia magna's protease SufA is a key virulence factor, degrading host defenses like fibrinogen and LL-37.
• Investigating stereoselective inhibitors of SufA is crucial for developing antivirulence agents.

Purpose of the Study:

• To synthesize and evaluate pure diastereoisomers of peptidyl 1-aminoalkylphosphonate diaryl esters as stereoselective inhibitors of SufA.
• To assess the efficacy of these compounds in reducing bacterial virulence and growth.
• To explore the potential of these inhibitors as antivirulence agents.

Main Methods:

• Synthesis and purification of diastereoisomers.
• Fluorescent enzymatic assays to determine SufA inhibition.
• SDS-PAGE to analyze inhibition of fibrinogen and LL-37 degradation.
• Molecular docking and Western blot to confirm binding interactions.

Main Results:

• Diastereoisomer XIIIA demonstrated significant SufA inhibition (63% at 50 μM) and protected fibrinogen and LL-37.
• XIIIA suppressed the growth of F. magna and E. coli.
• Molecular docking and Western blot confirmed XIIIA's binding to the SufA active site, while XIIIB showed minimal activity.

Conclusions:

• Stereochemistry is critical for SufA inhibition, with XIIIA being a potent inhibitor.
• XIIIA acts as an antivirulence agent by protecting host defense molecules.
• The validated probe offers a tool for identifying serine protease targets in other pathogens.