The role of glucosidase I (Cwh41p) in the biosynthesis of cell wall beta-1,6-glucan is indirect.
The role of glucosidase I (Cwh41p) in the biosynthesis of cell wall beta-1,6-glucan is indirect.
复制标题
葡萄糖苷酶 I (Cwh41p) 在细胞壁 β-1,6-葡聚糖生物合成中的作用是间接的。
DOI：
10.1091/mbc.9.10.2729
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发表时间：
1998
影响因子：
3.3
通讯作者：
Chen,LY
中科院分区：
文献类型：
--
作者：
Abeijon,C;Chen,LY
CWH 41是一个参与细胞壁β-1，6-葡聚糖组装的基因，最近被证明是酵母（Saccharomyces）葡糖苷酶I的结构基因，该酶I负责启动N-聚糖加工途径中末端α-1，2-葡萄糖残基的修剪。为了区分Cwh 41 p在β-1，6-葡聚糖生物合成中的直接或间接作用，我们构建了一个双突变体alg 5 Δ（缺乏多萜醇-β-葡萄糖合酶）cwh 41 Δ，发现它具有与alg 5 Δ单突变体相同的表型。它含有野生型水平的细胞壁β-1，6-葡聚糖，显示N-连接糖蛋白的中度糖基化不足，并在对cwh 41 Δ单突变体致死的Calcofluor白色（干扰细胞壁组装）浓度下生长。CWH 41与另外两个参与β-1，6-葡聚糖生物合成途径的基因KRE 6和KRE 1之间的强遗传相互作用在长醇-β-葡萄糖合酶（alg 5 Δ）缺失时消失。三重突变体5 Δ cwh 41 Δ kre 6 Δ是可行的，而在相同遗传背景下的双重突变体cwh 41 Δ kre 6 Δ是不可行的。在三重突变体5 Δ cwh 41 Δ kre 1 Δ中未观察到thech 41 Δ kre 1 Δ双突变体所特有的严重生长缓慢表型和75%的细胞壁β-1，6-葡聚糖减少。Kre 6p是一种假定的高尔基体葡聚糖合酶，在cwh 41 Δ菌株中不稳定，并且其过表达使这些细胞对Calcofluor白色具有抗性。这些结果表明，葡萄糖苷酶I（Cwh 41 p）在细胞壁β-1，6-葡聚糖的生物合成中的作用是间接的，长萜醇-β-葡萄糖不是该途径中的中间体。
CWH41, a gene involved in the assembly of cell wall β-1,6-glucan, has recently been shown to be the structural gene forSaccharomyces cerevisiaeglucosidase I that is responsible for initiating the trimming of terminal α-1,2-glucose residue in the N-glycan processing pathway. To distinguish between a direct or indirect role of Cwh41p in the biosynthesis of β-1,6-glucan, we constructed a double mutant,alg5Δ(lacking dolichol-P-glucose synthase)cwh41Δ, and found that it has the same phenotype as thealg5Δsingle mutant. It contains wild-type levels of cell wall β-1,6-glucan, shows moderate underglycosylation of N-linked glycoproteins, and grows at concentrations of Calcofluor White (which interferes with cell wall assembly) that are lethal tocwh41Δsingle mutant. The strong genetic interactions ofCWH41withKRE6andKRE1, two other genes involved in the β-1,6-glucan biosynthetic pathway, disappear in the absence of dolichol-P-glucose synthase (alg5Δ). The triple mutantalg5Δcwh41Δkre6Δis viable, whereas the double mutantcwh41Δkre6Δin the same genetic background is not. The severe slow growth phenotype and 75% reduction in cell wall β-1,6-glucan, characteristic of thecwh41Δkre1Δdouble mutant, are not observed in the triple mutantalg5Δcwh41Δkre1Δ. Kre6p, a putative Golgi glucan synthase, is unstable in cwh41Δ strains, and its overexpression renders these cells Calcofluor White resistant. These results demonstrate that the role of glucosidase I (Cwh41p) in the biosynthesis of cell wall β-1,6-glucan is indirect and that dolichol-P-glucose is not an intermediate in this pathway.