Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina 27710, USA.
Mol Microbiol. 2011 Sep;81(6):1560-76. doi: 10.1111/j.1365-2958.2011.07794.x. Epub 2011 Aug 23.
Cryptococcus neoformans is a human fungal pathogen that is the causative agent of cryptococcosis and fatal meningitis in immuno-compromised hosts. Recent studies suggest that copper (Cu) acquisition plays an important role in C. neoformans virulence, as mutants that lack Cuf1, which activates the Ctr4 high affinity Cu importer, are hypo-virulent in mouse models. To understand the constellation of Cu-responsive genes in C. neoformans and how their expression might contribute to virulence, we determined the transcript profile of C. neoformans in response to elevated Cu or Cu deficiency. We identified two metallothionein genes (CMT1 and CMT2), encoding cysteine-rich Cu binding and detoxifying proteins, whose expression is dramatically elevated in response to excess Cu. We identified a new C. neoformans Cu transporter, CnCtr1, that is induced by Cu deficiency and is distinct from CnCtr4 and which shows significant phylogenetic relationship to Ctr1 from other fungi. Surprisingly, in contrast to other fungi, we found that induction of both CnCTR1 and CnCTR4 expression under Cu limitation, and CMT1 and CMT2 in response to Cu excess, are dependent on the CnCuf1 Cu metalloregulatory transcription factor. These studies set the stage for the evaluation of the specific Cuf1 target genes required for virulence in C. neoformans.
新生隐球菌是一种人类真菌病原体，是免疫功能低下宿主中 cryptococcosis 和致命性脑膜炎的病原体。最近的研究表明，铜（Cu）的获取在新生隐球菌的毒力中起着重要作用，因为缺乏 Cuf1 的突变体（激活 Ctr4 高亲和力 Cu 进口器）在小鼠模型中表现出低毒力。为了了解新生隐球菌中对 Cu 有反应的基因组合以及它们的表达如何有助于毒力，我们确定了 C. neoformans 对升高的 Cu 或 Cu 缺乏的转录谱。我们鉴定了两个金属硫蛋白基因（CMT1 和 CMT2），它们编码富含半胱氨酸的 Cu 结合和解毒蛋白，其表达在响应过量 Cu 时显著升高。我们鉴定了一种新的 C. neoformans Cu 转运蛋白，CnCtr1，它由 Cu 缺乏诱导，与 CnCtr4 不同，与来自其他真菌的 Ctr1 具有显著的系统发育关系。令人惊讶的是，与其他真菌不同，我们发现 CnCTR1 和 CnCTR4 的表达在 Cu 限制下，以及 CMT1 和 CMT2 在 Cu 过量时的诱导，都依赖于 CnCuf1 Cu 金属调控转录因子。这些研究为评估新生隐球菌中对毒力至关重要的特定 Cuf1 靶基因奠定了基础。
