新型隐球酵母铜应答转录因子Cuf1与荚膜的生物合成相关性(英文)

Effect of the copper-responsive factor Cuf1 on the capsule biosynthesis in Cryptococcus neoformans

【目的】新型隐球酵母是人类条件致病真菌,主要感染免疫缺陷患者。该酵母最显著的特征是细胞外包被着多糖荚膜,这一重要致病因子的调控机制复杂。本文研究旨在阐述编码铜依赖转录因子的CUF1基因对其荚膜生物合成的负调控作用。【方法】以野生型菌株为对照,对CUF1缺失的突变菌株进行菌落形态观察、荚膜墨汁染色的显微观察、细胞聚沉试验以及荚膜定量分析。【结果】与野生型菌株相比,Δcuf1突变株产生的菌落更粘,显微镜下亦可明显观察到荚膜更厚。同样数量的细胞,突变株聚沉平衡后体积更大。此外,荚膜粗提物定量称重分析也证明突变株产生了更多的荚膜。并且外源铁可以回复Δcuf1突变株荚膜过量产生的表型。【结论】铜应答转录因子1(Cuf1)对荚膜的生物合成具有负调控作用。Cuf1可能通过铁的高亲和吸收途径调控铁吸收而实现该作用的。

[Objective] Cryptococcus neoformans is an opportunistic human fungal pathogen that primarily infects immunocompromised patients. The most distinctive feature of C. neoformans is that it contains a highly regulated major virulence factor, the polysaccharide capsule. We demonstrate in this paper that a copper-dependent transcription factor gene CUF1 has a negative role in capsule biosynthesis. [ Methods] Colony morphology, Indian inking staining microscopy, volume of cell suspension observation, weight of capsule produced by the disruption mutant of CUF1 and the wild type control. [ Results] The mutant produced a mucoid large colonies compared to that of the wild type. Capsule size was larger as shown by microscopy. The mutant had a larger volume with the same number of cells. And the mutant produced more capsule as determined by weight of dried extracellular polysaccharides. Iron repletion could suppress the capsule overproduction phenotype of the Acufl mutant. [ Conclusion ] The copper responsive transcription factor 1 （Cufl） negatively regulates capsule biosynthesis in C . neoformans . Cufl may act via modulating iron acquisition through the high-affinity iron uptake pathway.