The cell wall is a dynamic organelle which is tightly controlled for cell morphology, viability, and pathogenesis. It was previously shown that exocytosis is involved in the secretion of some components and enzymes of the cell wall. However, how the secretory pathway affects the cell wall integrity and assembly remains unclear. Here we show that the secretory pathway mutant (sec) cells were sensitive to cell wall antagonists in Saccharomyces cerevisiae, and they were lysed at restrictive conditions but can be rescued by osmotic stabilizers, indicating their cell walls were disrupted. Although glucans were reduced at the cell surface in sec mutants as speculated, the other two main cell wall components, chitins, and mannoproteins, were accumulated at the cell surface. We also found that both the protein level and the phosphorylation level of Slt2 increased in sec mutants. These results suggest that the exocytic pathway has a critical role in cell wall assembly. Our study will help to understand the mechanism of cell wall formation.

中文翻译：

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胞外途径在酵母细胞壁组装中的作用

细胞壁是一个动态的细胞器，对细胞形态、活力和发病机制进行严格控制。先前已表明胞吐作用与细胞壁某些成分和酶的分泌有关。然而，分泌途径如何影响细胞壁的完整性和组装仍不清楚。在这里，我们显示分泌途径突变体 ( sec ) 细胞对酿酒酵母中的细胞壁拮抗剂敏感，它们在限制条件下被裂解，但可以被渗透稳定剂拯救，表明它们的细胞壁被破坏。虽然葡聚糖在细胞表面在sec内被还原正如推测的突变体，其他两种主要的细胞壁成分，几丁质和甘露糖蛋白，在细胞表面积累。我们还发现sec突变体中 Slt2 的蛋白质水平和磷酸化水平都增加了。这些结果表明，胞吐途径在细胞壁组装中起关键作用。我们的研究将有助于了解细胞壁形成的机制。