Budding yeast septins are essential for cell division and polarity. Septins assemble as palindromic linear octameric complexes. The function and ultra-structural organization of septins are finely governed by their molecular polymorphism. In particular, in budding yeast, the end subunit can stand either as Shs1 or Cdc11. We have dissected, here, for the first time, the behavior of the Shs1 protomer bound to membranes at nanometer resolution, in complex with the other septins. Using electron microscopy, we have shown that on membranes, Shs1 protomers self-assemble into rings, bundles, filaments or two-dimensional gauzes. Using a set of specific mutants we have demonstrated a synergistic role of both nucleotides and lipids for the organization and oligomerization of budding yeast septins. Besides, cryo-electron tomography assays show that vesicles are deformed by the interaction between Shs1 oligomers and lipids. The Shs1-Shs1 interface is stabilized by the presence of phosphoinositides, allowing the visualization of micrometric long filaments formed by Shs1 protomers. In addition, molecular modeling experiments have revealed a potential molecular mechanism regarding the selectivity of septin subunits for phosphoinositide lipids.

中文翻译：

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核苷酸和脂质在Shs1 septin寡聚体自组装中的协同作用。

酵母菌种新芽对于细胞分裂和极性至关重要。Septins组装成回文线性八聚体。隔膜的功能和超微结构由其分子多态性很好地控制。特别是在发芽酵母中，末端亚基可以是Shs1或Cdc11。在这里，我们首次剖析了以纳米级分辨率结合其他隔膜的Shs1前体在膜上的行为。使用电子显微镜，我们已经证明Shs1前列腺素在膜上会自组装成环，束，细丝或二维网。使用一组特定的突变体，我们已经证明了核苷酸和脂质对于发芽的酵母分离蛋白的组织和寡聚化的协同作用。除了，低温电子层析成像分析显示，囊泡因Shs1寡聚物和脂质之间的相互作用而变形。Shs1-Shs1界面通过磷酸肌醇的存在得以稳定，从而可以看到由Shs1前体形成的微米级长丝。此外，分子建模实验已经揭示了关于Septin亚基对磷酸肌醇脂质选择性的潜在分子机制。