Coupling cell wall expansion with cell growth is a universal challenge faced by walled organisms. Mutations in Schizosaccharomyces pombe css1, which encodes a PM inositol phosphosphingolipid phospholipase C, prevent cell wall expansion but not synthesis of cell wall material. To probe how Css1 modulates cell wall formation we used classical and chemical genetics coupled with quantitative mass spectrometry. We found that elevated levels of the sphingolipid biosynthetic pathway's final product, mannosylinositol phosphorylceramide (MIPC), specifically correlated with the css1-3 phenotype. We also found that an apparent indicator of sphingolipids and a sterol biosensor accumulated at the cytosolic face of the PM at cell tips and the division site of css1-3 cells and, in accord, the PM in css1-3 was less dynamic than in wildtype cells. Interestingly, disrupting the protein glycosylation machinery recapitulated the css1-3 phenotype and led us to investigate Ghs2, a glycosylated PM protein predicted to modify cell wall material. Disrupting Ghs2 function led to aberrant cell wall material accumulation suggesting Ghs2 is dysfunctional in css1-3. We conclude that preventing an excess of MIPC in the S. pombe PM is critical to the function of key PM-localized proteins necessary for coupling growth with cell wall formation.

中文翻译：

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质膜中鞘脂 MIPC 水平升高会破坏裂殖酵母中细胞生长与细胞壁形成的协调。

将细胞壁扩张与细胞生长耦合是有壁生物面临的普遍挑战。粟酒裂殖酵母 css1（编码 PM 肌醇磷酸鞘脂磷脂酶 C）的突变会阻止细胞壁扩张，但不会阻止细胞壁材料的合成。为了探究 Css1 如何调节细胞壁形成，我们使用了经典遗传学和化学遗传学以及定量质谱法。我们发现鞘脂生物合成途径的最终产物甘露糖肌醇磷酸神经酰胺 (MIPC) 水平升高与 css1-3 表型特别相关。我们还发现，鞘脂和甾醇生物传感器的明显指示剂积聚在细胞尖端的 PM 的胞质表面和 css1-3 细胞的分裂位点，因此，css1-3 中的 PM 的动态性低于野生型细胞。有趣的是，破坏蛋白质糖基化机制重现了 css1-3 表型，并促使我们研究 Ghs2，一种预计能修饰细胞壁材料的糖基化 PM 蛋白。破坏 Ghs2 功能会导致异常的细胞壁物质积累，表明 Ghs2 在 css1-3 中功能失调。我们的结论是，防止粟酒裂殖酵母 PM 中 MIPC 过量对于关键 PM 定位蛋白的功能至关重要，这些蛋白是耦合生长与细胞壁形成所必需的。