Toyo University, Itakura, Oura-gun, Gunma 374-0193, Japan.
Fungal Genet Biol. 2013 Mar;52:65-72. doi: 10.1016/j.fgb.2012.12.001. Epub 2012 Dec 27.
GPI(glycosylphosphatidylinositol)-anchored beta-(1,3)-glucanosyltransferases play an active role in cell wall biosynthesis in fungi. Neurospora crassa has 5 putative beta-(1,3)-glucanosyltransferase genes, namely, gel-1, gel-2, gel-3, gel-4, and gel-5, in its genome. Among them, the gel-3 gene is constitutively expressed at the highest level in growing hyphae, whereas gel-1 is expressed at the lowest level. The gel-3 deletion mutant displayed slow growth, while other gel gene disruptants exhibited normal growth. Although no gel gene disruption affected pH sensitivity and fertility, all Δgel mutants were resistant to cell wall degradation enzymes. Micafungin, a beta-(1,3)-glucan synthase inhibitor, induced gel-4 expression in the wild-type and 2 MAP kinase mutants mak-1 and mak-2 strains. In contrast, fludioxonil, an activator of OS-2 MAP kinase, strongly induced the gel-1 gene in the wild-type strain. Its induction was nearly abolished in the os-2 and in the atf-1/asl-1 mutant. These suggested that GEL-3 is a major factor in mycelial growth, while GEL-1 and GEL-4 may play important roles in cell wall remodeling in response to stress conditions or cell wall damage, respectively.
糖基磷脂酰肌醇（GPI）锚定的β-（1,3）-葡聚糖基转移酶在真菌细胞壁生物合成中发挥积极作用。粗糙脉孢菌（Neurospora crassa）在其基因组中有 5 个假定的β-（1,3）-葡聚糖基转移酶基因，即 gel-1、gel-2、gel-3、gel-4 和 gel-5。其中，gel-3 基因在生长菌丝中以最高水平组成型表达，而 gel-1 表达水平最低。gel-3 缺失突变体生长缓慢，而其他 gel 基因敲除突变体生长正常。虽然没有 gel 基因敲除影响 pH 敏感性和育性，但所有Δgel 突变体均对细胞壁降解酶具有抗性。β-（1,3）-葡聚糖合酶抑制剂米卡芬净诱导野生型和 2 个 MAP 激酶突变体 mak-1 和 mak-2 菌株中的 gel-4 表达。相比之下，OS-2 MAP 激酶激活剂氟啶酮在野生型菌株中强烈诱导 gel-1 基因的表达。在 os-2 和 atf-1/asl-1 突变体中，其诱导几乎被消除。这表明 GEL-3 是菌丝生长的主要因素，而 GEL-1 和 GEL-4 可能分别在细胞壁重塑和应对应激条件或细胞壁损伤中发挥重要作用。
