Structure-Guided Discovery of Potent Antifungals that Prevent Ras Signaling by Inhibiting Protein Farnesyltransferase

Area of Science:

• Medicinal Chemistry
• Mycology
• Molecular Biology

Background:

• Fungal infections pose a significant threat due to limited treatment options and increasing antifungal resistance.
• Developing novel antifungal agents is crucial to combat life-threatening fungal pathogens like Cryptococcus neoformans.

Purpose of the Study:

• To develop and characterize novel compounds that inhibit protein farnesyltransferase, targeting the farnesylation of Cryptococcus neoformans Ras protein.
• To evaluate the antifungal efficacy and mechanism of action of these novel inhibitors.

Main Methods:

• Synthesis and characterization of small molecule inhibitors targeting protein farnesyltransferase.
• Determination of inhibitor binding affinities (nanomolar) and minimum inhibitory concentrations (MICs) against Cryptococcus neoformans.
• Elucidation of inhibitor binding modes and mechanisms of action using structural and biochemical analyses.

Main Results:

• Developed high-affinity inhibitors (3-4 nM) of protein farnesyltransferase, preventing Ras protein farnesylation.
• Achieved potent inhibition of fungal growth (3-6 µM MICs), outperforming Fluconazole by 4-8 fold.
• Identified distinct binding mechanisms and conformations, demonstrating that potency is linked to inhibition strategy efficacy at low enzyme/substrate levels.

Conclusions:

• Novel inhibitors targeting fungal Ras farnesylation represent a promising class of next-generation antifungals.
• Understanding the structure-activity relationships and inhibition mechanisms is key to optimizing antifungal potency.
• Chemical modifications can be strategically employed to encode desired inhibitor conformations and enhance efficacy against fungal pathogens.