Unité des Aspergillus, Institut Pasteur, Paris, France.
Unité des Aspergillus, Institut Pasteur, Paris, France
mSphere. 2019 Jul 31;4(4):e00397-19. doi: 10.1128/mSphere.00397-19.
The fungal cell wall is a complex and dynamic entity essential for the development of fungi. It is composed mainly of polysaccharides that are synthetized by protein complexes. At the cell wall level, enzyme activities are involved in postsynthesis polysaccharide modifications such as cleavage, elongation, branching, and cross-linking. Glycosylphosphatidylinositol (GPI)-anchored proteins have been shown to participate in cell wall biosynthesis and specifically in polysaccharide remodeling. Among these proteins, the DFG family plays an essential role in controlling polar growth in yeast. In the filamentous fungus and opportunistic human pathogen , the gene family contains seven orthologous genes among which only six are expressed under growth conditions. Deletions of single genes revealed that plays the most important morphogenetic role in this gene family. A sextuple-deletion mutant resulting from the deletion of all expressed genes did not contain galactomannan in the cell wall and has severe growth defects. This study has shown that DFG members are absolutely necessary for the insertion of galactomannan into the cell wall of and that the proper cell wall localization of the galactomannan is essential for correct fungal morphogenesis in The fungal cell wall is a complex and dynamic entity essential for the development of fungi. It is composed mainly of polysaccharides that are synthetized by protein complexes. Enzymes involved in postsynthesis polysaccharide modifications, such as cleavage, elongation, branching, and cross-linking, are essential for fungal life. Here, we investigated in the role of the members of the Dfg family, one of the 4 GPI-anchored protein families common to yeast and molds involved in cell wall remodeling. Molecular and biochemical approaches showed that DFG members are required for filamentous growth, conidiation, and cell wall organization and are essential for the life of this fungal pathogen.
真菌细胞壁是真菌发育所必需的复杂而动态的实体。它主要由多糖组成，这些多糖由蛋白质复合物合成。在细胞壁水平上，酶活性参与多糖的后合成修饰，如切割、延伸、分支和交联。已经表明糖基磷脂酰肌醇（GPI）锚定蛋白参与细胞壁生物合成，特别是多糖重塑。在这些蛋白质中，DFG 家族在控制酵母的极性生长中起着至关重要的作用。在丝状真菌和机会性病原体中，该基因家族包含七个直系同源基因，其中只有六个在生长条件下表达。单个基因缺失表明，在这个基因家族中，扮演着最重要的形态发生作用。由于删除所有表达的基因而导致的六重缺失突变体在细胞壁中不含半乳甘露聚糖，并且生长缺陷严重。这项研究表明，DFG 成员对于将半乳甘露聚糖插入的细胞壁是绝对必要的，并且半乳甘露聚糖在细胞壁中的适当定位对于正确的真菌形态发生是必不可少的。
