Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China.
Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China; Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Wuhan, China.
Fungal Genet Biol. 2020 Nov;144:103467. doi: 10.1016/j.fgb.2020.103467. Epub 2020 Sep 28.
Tos7 (Yol019w) is a Sur7/PalI family transmembrane protein in the budding yeast Saccharomyces cerevisiae. Since the deletion of TOS7 did not affect growth or cell morphology, the cellular roles of Tos7 have not been established previously. Here, we show that high-copy TOS7 expression suppressed the growth defect of the secretion-defective RGA1-C term-overexpressing mutant and sec15-1 mutant. Moreover, Tos7 physically interacted with Boi2 and the Rho GTPase Rho3, two key regulators of exocyst assembly, suggesting that Tos7 plays a role in secretion. We also show that the deletion of TOS7 rendered the cells more sensitive to the cell wall-disrupting agents Congo red and calcofluor white while high-copy TOS7 expression had an opposite effect, suggesting that Tos7 affects cell wall organization. Finally, we show that Tos7 localized to punctate patches on the plasma membrane that were largely co-localized with the plasma membrane microdomains named MCC (membrane compartment of Can1). Together, these results suggest that Tos7 contributes to cell surface-related functions. Tos7 is likely an auxiliary component of MCC/eisosome that specifically interacts with the secretory pathway.
Tos7（Yol019w）是酿酒酵母芽殖酵母中 Sur7/PalI 家族的跨膜蛋白。由于 Tos7 的缺失并不影响生长或细胞形态，因此之前尚未确定 Tos7 的细胞功能。在这里，我们发现高拷贝 Tos7 表达可抑制分泌缺陷的 RGA1-C 末端过表达突变体和 sec15-1 突变体的生长缺陷。此外，Tos7 与 Boi2 和 Rho GTPase Rho3 相互作用，这两种蛋白都是外泌体组装的关键调节剂，表明 Tos7 在分泌过程中发挥作用。我们还发现 Tos7 的缺失使细胞对破坏细胞壁的刚果红和 Calcofluor White 更加敏感，而高拷贝 Tos7 表达则有相反的效果，表明 Tos7 影响细胞壁组织。最后，我们发现 Tos7 定位于质膜上的点状斑块上，这些斑块与 Can1 命名的膜区室（membrane compartment of Can1，MCC）的质膜微区域大部分共定位。综上所述，这些结果表明 Tos7 有助于细胞表面相关功能。Tos7 可能是 MCC/eisosome 的辅助成分，它与分泌途径特异性相互作用。
