Cisplatin protects mice from challenge of Cryptococcus neoformans by targeting the Prp8 intein

Area of Science:

• Molecular Biology
• Mycology
• Drug Discovery

Background:

• The Prp8 intein is prevalent in pathogenic fungi like *Cryptococcus* and *Aspergillus*.
• Prp8 protein is essential for fungal cellular functions, making its intein a potential drug target.
• A Prp8 intein inhibitor represents a novel antifungal therapeutic strategy.

Purpose of the Study:

• To investigate cisplatin as a potential inhibitor of the Prp8 intein.
• To explore the Prp8 intein as a novel antifungal target.
• To elucidate the mechanism of cisplatin's antifungal activity.

Main Methods:

• Fungal growth inhibition assays with cisplatin on *C. neoformans*, *C. gattii*, and *Candida* species.
• In vitro splicing assays to assess cisplatin's effect on Prp8 intein activity.
• Crystallography to determine the binding site of cisplatin on the Prp8 intein.
• Site-directed mutagenesis to confirm the role of active site residues.

Main Results:

• Cisplatin significantly inhibited the growth of Prp8 intein-containing fungi (*C. neoformans*, *C. gattii*) but not intein-free *Candida* species.
• Cisplatin demonstrated antifungal activity in a *C. neoformans* mouse model.
• Cisplatin directly binds to the Prp8 intein active site, inhibiting splicing in a dose-dependent manner.
• Mutations at the splicing site abolished cisplatin binding and intein splicing.
• Overexpression of the Prp8 intein conferred cisplatin resistance in cryptococcal species.

Conclusions:

• Cisplatin exhibits specific antifungal activity by inhibiting the Prp8 intein.
• The Prp8 intein is a validated novel antifungal target.
• Cisplatin's mechanism involves direct binding and inhibition of Prp8 intein splicing.