State Key Laboratory of Systems Medicine for Cancer, Center for Single-Cell Omics, School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
Department of Gastroenterology, The Shanghai Tenth People's Hospital, Department of Bioinformatics, School of Life Sciences and Technology, Tongji University, Shanghai, China.
Nat Commun. 2024 Feb 27;15(1):1757. doi: 10.1038/s41467-024-46141-x.
Candidalysin, a cytolytic peptide toxin secreted by the human fungal pathogen Candida albicans, is critical for fungal pathogenesis. Yet, its intracellular targets have not been extensively mapped. Here, we performed a high-throughput enhanced yeast two-hybrid (HT-eY2H) screen to map the interactome of all eight Ece1 peptides with their direct human protein targets and identified a list of potential interacting proteins, some of which were shared between the peptides. CCNH, a regulatory subunit of the CDK-activating kinase (CAK) complex involved in DNA damage repair, was identified as one of the host targets of candidalysin. Mechanistic studies revealed that candidalysin triggers a significantly increased double-strand DNA breaks (DSBs), as evidenced by the formation of γ-H2AX foci and colocalization of CCNH and γ-H2AX. Importantly, candidalysin binds directly to CCNH to activate CAK to inhibit DNA damage repair pathway. Loss of CCNH alleviates DSBs formation under candidalysin treatment. Depletion of candidalysin-encoding gene fails to induce DSBs and stimulates CCNH upregulation in a murine model of oropharyngeal candidiasis. Collectively, our study reveals that a secreted fungal toxin acts to hijack the canonical DNA damage repair pathway by targeting CCNH and to promote fungal infection.
白色念珠菌是一种能分泌细胞溶解肽毒素的人类真菌病原体，这种毒素对于真菌感染的发病机制至关重要。然而，其细胞内靶标尚未得到广泛的研究。在这里，我们进行了高通量增强型酵母双杂交（HT-eY2H）筛选，以绘制所有 8 种 Ece1 肽与其直接人类蛋白靶标的相互作用组，并鉴定了一系列潜在的相互作用蛋白，其中一些肽之间存在共享蛋白。CCNH 是参与 DNA 损伤修复的 CDK 激活激酶（CAK）复合物的调节亚基，被鉴定为念珠菌毒素的一个宿主靶标。机制研究表明，念珠菌毒素可引发明显增加的双链 DNA 断裂（DSBs），这表现在 γ-H2AX 焦点的形成和 CCNH 与 γ-H2AX 的共定位。重要的是，念珠菌毒素可直接与 CCNH 结合，激活 CAK 抑制 DNA 损伤修复途径。在念珠菌毒素处理下，CCNH 的缺失可减轻 DSBs 的形成。在口咽念珠菌病的小鼠模型中，缺失编码念珠菌毒素的基因不会诱导 DSBs 的形成，反而会刺激 CCNH 的上调。总之，我们的研究揭示了一种分泌性真菌毒素通过靶向 CCNH 来劫持经典的 DNA 损伤修复途径，并促进真菌感染的机制。
