Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Microbiology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China.
Fungal Genet Biol. 2017 Oct;107:31-43. doi: 10.1016/j.fgb.2017.08.003. Epub 2017 Aug 10.
Copper (Cu) is an essential trace element and is regarded as an important virulence factor in fungal pathogens. Previous studies suggest that a putative Cu-sensing transcription factor Mac1 and the Cu transporter Ctr family play important roles during fungal development and virulence. However, how Cu importers of the Ctr family are involved in the Cu acquisition and what is the functional relationship between them have not been fully investigated yet. Here, we demonstrate that the yeast Mac1 homolog in the opportunistic human pathogen Aspergillus fumigatus is required during colony development under low Cu conditions. Transcriptional profiling combined with LacZ reporter analyses indicate that Cu transporters ctrA2 and ctrC are expressed in an Afmac1-dependent manner upon Cu starvation, and over-expression of ctrA2 or ctrC transporters almost completely rescue the Afmac1-deletion defects, suggesting a redundancy of both transporters in Afmac1-mediated Cu uptake. Genetic analysis showed that ctrC may play a dominant role against Cu starvation relative to ctrA2 and elevated expression of ctrA2 can compensate for ctrC deletion under Cu starvation. Interestingly, both ctrA2 and ctrC deletions can suppress ctrB deletion colony defects. Our findings suggest that Ctr family proteins might coordinately regulate their functions to adapt to different Cu environments. Compared to yeast homologs, Cu family proteins in A. fumigatus may have their own working styles. Most importantly, the Afmac1 deletion strain shows a significantly attenuated pathogenicity in the neutropenic immunocompromised (a combination of cyclophosphamide and hydrocortisone) mice model, demonstrating that Afmac1 is required for pathogenesis in vivo.
铜（Cu）是一种必需的微量元素，被认为是真菌病原体的重要毒力因子。先前的研究表明，一个假定的 Cu 感应转录因子 Mac1 和 Cu 转运蛋白 Ctr 家族在真菌发育和毒力中发挥重要作用。然而，Ctr 家族的 Cu 进口器如何参与 Cu 的获取，以及它们之间的功能关系尚未得到充分研究。在这里，我们证明了机会性人类病原体烟曲霉中的酵母 Mac1 同源物在低 Cu 条件下的菌落发育过程中是必需的。转录谱分析结合 LacZ 报告基因分析表明，Cu 转运蛋白 ctrA2 和 ctrC 在 Cu 饥饿时以 Afmac1 依赖的方式表达，并且 ctrA2 或 ctrC 转运蛋白的过表达几乎完全挽救了 Afmac1 缺失缺陷，表明这两种转运蛋白在 Afmac1 介导的 Cu 摄取中具有冗余性。遗传分析表明，相对于 ctrA2，ctrC 在对抗 Cu 饥饿方面可能发挥主导作用，并且在 Cu 饥饿下，ctrA2 的高表达可以补偿 ctrC 缺失。有趣的是，ctrA2 和 ctrC 的缺失都可以抑制 ctrB 缺失的菌落缺陷。我们的研究结果表明，Ctr 家族蛋白可能协同调节其功能以适应不同的 Cu 环境。与酵母同源物相比，烟曲霉中的 Cu 家族蛋白可能具有自己的工作方式。最重要的是，Afmac1 缺失株在中性粒细胞减少免疫功能低下（环磷酰胺和氢化可的松的组合）小鼠模型中表现出明显减弱的致病性，表明 Afmac1 是体内发病所必需的。
