Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca and Departamento de Microbiología y Genética, Universidad de Salamanca, C/Zacarías González s/n., Salamanca, Spain.
Microbiologyopen. 2013 Oct;2(5):778-94. doi: 10.1002/mbo3.113. Epub 2013 Jul 30.
Sensing stressful conditions that affect the cell wall reorganization is important for yeast survival. Here, we studied two proteins SpWsc1p and SpMtl2p with structural features indicative of plasma membrane-associated cell wall sensors. We found that Mtl2p and Wsc1p act by turning on the Rho1p GTPase. Each gene could be deleted individually without affecting viability, but the deletion of both was lethal and this phenotype was rescued by overexpression of the genes encoding either Rho1p or its GDP/GTP exchange factors (GEFs). In addition, wsc1Δ and mtl2Δ cells showed a low level of Rho1p-GTP under cell wall stress. Mtl2p-GFP (green fluorescent protein) localized to the cell periphery and was necessary for survival under different types of cell wall stress. Wsc1p-GFP was concentrated in patches at the cell tips, it interacted with the Rho-GEF Rgf2p, and its overexpression activated cell wall biosynthesis. Our results are consistent with the notion that cell wall assembly is regulated by two different networks involving Rho1p. One includes signaling from Mtl2p through Rho1p to Pck1p, while the second one implicates signaling from Wsc1p and Rgf2p through Rho1p to activate glucan synthase (GS). Finally, signaling through the mitogen-activated protein kinase (MAPK) Pmk1p remained active in mtl2Δ and wsc1Δ disruptants exposed to cell wall stress, suggesting that the cell wall stress-sensing spectrum of Schizosaccharomyces pombe sensor-like proteins differs from that of Saccharomyces cerevisiae.
感知影响细胞壁重组的应激条件对酵母的生存很重要。在这里，我们研究了两个具有结构特征的蛋白质 SpWsc1p 和 SpMtl2p，它们暗示是与质膜相关的细胞壁传感器。我们发现 Mtl2p 和 Wsc1p 通过激活 Rho1p GTPase 发挥作用。每个基因都可以单独缺失而不影响生存能力，但两者的缺失都是致命的，并且这种表型可以通过过表达编码 Rho1p 或其 GDP/GTP 交换因子（GEF）的基因来挽救。此外，wsc1Δ 和 mtl2Δ 细胞在细胞壁应激下表现出低水平的 Rho1p-GTP。Mtl2p-GFP（绿色荧光蛋白）定位于细胞边缘，在不同类型的细胞壁应激下对生存是必需的。Wsc1p-GFP 集中在细胞尖端的斑点中，它与 Rho-GEF Rgf2p 相互作用，其过表达激活细胞壁生物合成。我们的结果与以下观点一致，即细胞壁组装受两个不同的网络调节，涉及 Rho1p。一个网络包括 Mtl2p 通过 Rho1p 向 Pck1p 的信号传递，而另一个网络则暗示 Wsc1p 和 Rgf2p 通过 Rho1p 向激活葡聚糖合酶（GS）的信号传递。最后，在暴露于细胞壁应激的 mtl2Δ 和 wsc1Δ 突变体中，丝裂原激活蛋白激酶（MAPK）Pmk1p 的信号传递仍然活跃，这表明裂殖酵母传感器样蛋白的细胞壁应激感应谱与酿酒酵母不同。
