Spreghini Elisabetta, Davis Dana A, Subaran Ryan, Kim Michelle, Mitchell Aaron P
Department of Microbiology and Institute of Cancer Research, Columbia University, New York, New York 10032, USA.
Eukaryot Cell. 2003 Aug;2(4):746-55. doi: 10.1128/EC.2.4.746-755.2003.
The Candida albicans cell wall participates in both growth and morphological transitions between yeast and hyphae. Our studies here focus on Dfg5p and Dcw1p, two similar proteins with features of glycosylphosphatidylinositol-linked cell surface proteins. Mutants lacking Dfg5p are defective in alkaline pH-induced hypha formation; mutants lacking Dcw1p have no detected hypha formation defect. Both homozygote-triplication tests and conditional expression strategies indicate that dfg5 and dcw1 mutations are synthetically lethal. Therefore, Dfg5p and Dcw1p share a function required for growth. Epitope-tagged Dfg5p, created through an insertional mutagenesis strategy, is found in cell membrane and cell wall extract fractions, and endoglycosidase H digestion shows that Dfg5p undergoes N-linked mannosylation. Surprisingly, Dfg5p is required for expression of the hypha-specific gene HWP1 in alkaline media. Because Dfg5p is a cell surface protein, it is poised to generate or transmit an external signal required for the program of hypha-specific gene expression.
白色念珠菌的细胞壁参与酵母和菌丝之间的生长及形态转变。我们在此的研究聚焦于Dfg5p和Dcw1p，这两种具有糖基磷脂酰肌醇连接细胞表面蛋白特征的相似蛋白。缺乏Dfg5p的突变体在碱性pH诱导的菌丝形成方面存在缺陷；缺乏Dcw1p的突变体未检测到菌丝形成缺陷。纯合三倍体测试和条件表达策略均表明dfg5和dcw1突变是合成致死的。因此，Dfg5p和Dcw1p共享生长所需的功能。通过插入诱变策略产生的表位标记Dfg5p存在于细胞膜和细胞壁提取物组分中，内切糖苷酶H消化显示Dfg5p经历N - 连接的甘露糖基化。令人惊讶的是，在碱性培养基中，Dfg5p是菌丝特异性基因HWP1表达所必需的。由于Dfg5p是一种细胞表面蛋白，它有可能产生或传递菌丝特异性基因表达程序所需的外部信号。
