An unusual feature of the opportunistic pathogen C. albicans is its ability to stochastically switch between two distinct, heritable cell types called white and opaque. Here, we show that only opaque cells, in response to environmental signals, massively up-regulate a specific group of secreted proteases and peptide transporters, allowing exceptionally efficient use of proteins as sources of nitrogen. We identify the specific proteases (members of the secreted aspartyl protease (SAP) family) needed for opaque cells to proliferate under these conditions, and we identify four transcriptional regulators of this specialized proteolysis and uptake program. We also show that, in mixed cultures, opaque cells enable white cells to also proliferate efficiently when proteins are the sole nitrogen source. Based on these observations, we suggest that one role of white-opaque switching is to create mixed populations where the different phenotypes derived from a single genome are shared between two distinct cell types.

中文翻译：

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分泌蛋白酶和转运蛋白的不透明细胞特异性表达程序允许白色念珠菌中的细胞类型合作。

机会性病原体白色念珠菌的一个不寻常特征是它能够在两种不同的、可遗传的细胞类型（白色和不透明）之间随机切换。在这里，我们表明，只有不透明细胞响应环境信号，大量上调一组特定的分泌蛋白酶和肽转运蛋白，从而能够极其有效地利用蛋白质作为氮源。我们确定了不透明细胞在这些条件下增殖所需的特定蛋白酶（分泌性天冬氨酰蛋白酶 ( SAP ) 家族的成员），并且我们确定了这种专门的蛋白水解和摄取程序的四种转录调节因子。我们还表明，在混合培养物中，当蛋白质是唯一的氮源时，不透明细胞也能使白细胞有效增殖。基于这些观察，我们认为白色-不透明转换的作用之一是创建混合群体，其中源自单个基因组的不同表型在两种不同的细胞类型之间共享。