The Prp8 intein is one of the most widespread eukaryotic inteins, present in important pathogenic fungi, including Cryptococcus and Aspergillus species. Because the processed Prp8 carries out essential and non-redundant cellular functions, a Prp8 intein inhibitor is a mechanistically novel antifungal agent. In this report, we demonstrated that cisplatin, an FDA-approved cancer drug, significantly arrested growth of Prp8 intein-containing fungi C. neoformans and C. gattii, but only poorly inhibited growth of intein-free Candida species. These results suggest that cisplatin arrests fungal growth through specific inhibition of the Prp8 intein. Cisplatin was also found to significantly inhibit growth of C. neoformans in a mouse model. Our results further showed that cisplatin inhibited Prp8 intein splicing in vitro in a dose-dependent manner by direct binding to the Prp8 intein. Crystal structures of the apo- and cisplatin-bound Prp8 inteins revealed that two degenerate cisplatin molecules bind at the intein active site. Mutation of the splicing-site residues led to loss of cisplatin binding, as well as impairment of intein splicing. Finally, we found that overexpression of the Prp8 intein in cryptococcal species conferred cisplatin resistance. Overall, these results indicate that the Prp8 intein is a novel antifungal target worth further investigation.

中文翻译：

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顺铂通过靶向 Prp8 内含肽来保护小鼠免受新型隐球菌的攻击。

Prp8 内含肽是最广泛的真核内含肽之一，存在于重要的病原真菌中，包括隐球菌和曲霉属物种。由于加工后的 Prp8 执行重要且非冗余的细胞功能，因此 Prp8 内含肽抑制剂是​​一种机制新颖的抗真菌剂。在本报告中，我们证明顺铂（FDA 批准的抗癌药物）可显着抑制含 Prp8 内含肽的真菌新型念珠菌和格特念珠菌的生长，但对不含内含肽的念珠菌属的生长抑制效果较差。这些结果表明顺铂通过特异性抑制 Prp8 内含肽来阻止真菌生长。顺铂还被发现能显着抑制小鼠模型中新型隐球菌的生长。我们的结果进一步表明，顺铂通过直接结合 Prp8 内含肽，以剂量依赖性方式在体外抑制 Prp8 内含肽剪接。结合 apo 和顺铂的 Prp8 内含肽的晶体结构表明，两个简并顺铂分子在内含肽活性位点结合。剪接位点残基的突变导致顺铂结合丧失，以及内含肽剪接受损。最后，我们发现隐球菌物种中 Prp8 内含肽的过度表达会赋予顺铂耐药性。总的来说，这些结果表明 Prp8 内含肽是一个值得进一步研究的新型抗真菌靶点。