Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, 422-8529, Japan.
Department of Agriculture, Shizuoka University, Shizuoka, 422-8529, Japan.
Sci Rep. 2023 Sep 27;13(1):16187. doi: 10.1038/s41598-023-43232-5.
Vacuoles change their morphology in response to stress. In yeast exposed to chronically high temperatures, vacuolar membranes get deformed and invaginations are formed. We show that phase-separation of vacuolar membrane occurred after heat stress leading to the formation of the invagination. In addition, Hfl1, a vacuolar membrane-localized Atg8-binding protein, was found to suppress the excess vacuolar invaginations after heat stress. At that time, Hfl1 formed foci at the neck of the invaginations in wild-type cells, whereas it was efficiently degraded in the vacuole in the atg8Δ mutant. Genetic analysis showed that the endosomal sorting complex required for transport machinery was necessary to form the invaginations irrespective of Atg8 or Hfl1. In contrast, a combined mutation with the vacuole BAR domain protein Ivy1 led to vacuoles in hfl1Δivy1Δ and atg8Δivy1Δ mutants having constitutively invaginated structures; moreover, these mutants showed stress-sensitive phenotypes. Our findings suggest that vacuolar invaginations result from the combination of changes in the physiochemical properties of the vacuolar membrane and other cellular factors.
液泡会根据压力改变形态。在长期处于高温环境的酵母中，液泡膜会变形并出现内陷。我们发现，热应激后液泡膜发生了相分离，导致了内陷的形成。此外，我们还发现，定位于液泡膜的 Atg8 结合蛋白 Hfl1 可以抑制热应激后液泡的过度内陷。在野生型细胞中，Hfl1 在内陷的颈部形成焦点，而在 atg8Δ 突变体中，Hfl1 则被有效地降解在液泡中。遗传分析表明，内体分选复合物所需的运输机制对于形成内陷是必要的，而与 Atg8 或 Hfl1 无关。相比之下，与液泡 BAR 结构域蛋白 Ivy1 的联合突变导致 hfl1Δivy1Δ 和 atg8Δivy1Δ 突变体中的液泡具有持续内陷的结构；此外，这些突变体还表现出应激敏感的表型。我们的研究结果表明，液泡内陷是由液泡膜物理化学性质的变化和其他细胞因素共同作用的结果。
