Sharmin Dilruba, Sasano Yu, Sugiyama Minetaka, Harashima Satoshi
Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
J Biosci Bioeng. 2015 Apr;119(4):392-8. doi: 10.1016/j.jbiosc.2014.09.013. Epub 2014 Nov 10.
The phosphorylation status of cellular proteins results from an equilibrium between the activities of protein kinases and protein phosphatases (PPases). Reversible protein phosphorylation is an important aspect of signal transduction that regulate many biological processes in eukaryotic cells. The Saccharomyces cerevisiae genome encodes 40 PPases, including seven members of the protein phosphatase 2C subfamily (PTC1 to PTC7). In contrast to other PPases, the cellular roles of PTCs have not been investigated in detail. Here, we sought to determine the cellular role of PTC6 in S. cerevisiae with disruption of PTC genes. We found that cells with Δptc6 disruption were tolerant to the cell wall-damaging agents Congo red (CR) and calcofluor white (CFW); however, cells with simultaneous disruption of PTC1 and PTC6 were very sensitive to these agents. Thus, simultaneous disruption of PTC1 and PTC6 gave a synergistic response to cell wall damaging agents. The level of phosphorylated Slt2 increased significantly after CR treatment in Δptc1 cells and more so in Δptc1Δptc6 cells; therefore, deletion of PTC6 enhanced Slt2 phosphorylation in the Δptc1 disruptant. The level of transcription of KDX1 upon exposure to CR increased to a greater extent in the Δptc1Δptc6 double disruptant than the Δptc1 single disruptant. The Δptc1Δptc6 double disruptant cells showed normal vacuole formation under standard growth conditions, but fragmented vacuoles were present in the presence of CR or CFW. Our analyses indicate that S. cerevisiae PTC6 participates in the negative regulation of Slt2 phosphorylation and vacuole morphogenesis under cell wall stress conditions.
细胞蛋白质的磷酸化状态源于蛋白激酶和蛋白磷酸酶（PPases）活性之间的平衡。可逆性蛋白质磷酸化是信号转导的一个重要方面，它调节真核细胞中的许多生物学过程。酿酒酵母基因组编码40种PPases，包括蛋白磷酸酶2C亚家族（PTC1至PTC7）的7个成员。与其他PPases不同，PTCs的细胞作用尚未得到详细研究。在这里，我们试图通过破坏PTC基因来确定酿酒酵母中PTC6的细胞作用。我们发现，Δptc6破坏的细胞对细胞壁损伤剂刚果红（CR）和荧光增白剂（CFW）具有耐受性；然而，同时破坏PTC1和PTC6的细胞对这些试剂非常敏感。因此，同时破坏PTC1和PTC6对细胞壁损伤剂产生了协同反应。在Δptc1细胞中，CR处理后磷酸化Slt2的水平显著增加，在Δptc1Δptc6细胞中更是如此；因此，缺失PTC6增强了Δptc1破坏体中Slt2的磷酸化。暴露于CR后，KDX1的转录水平在Δptc1Δptc6双破坏体中比Δptc1单破坏体中增加得更多。在标准生长条件下，Δptc1Δptc6双破坏体细胞显示出正常的液泡形成，但在存在CR或CFW的情况下存在碎片化的液泡。我们的分析表明，酿酒酵母PTC6在细胞壁应激条件下参与Slt2磷酸化和液泡形态发生的负调控。
