Dissecting the protein kinase C/MAP kinase signalling pathway of Saccharomyces cerevisiae.
Dissecting the protein kinase C/MAP kinase signalling pathway of Saccharomyces cerevisiae.
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发表时间：
1994
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通讯作者：
D. E. Levin;B. Bowers;C. Y. Chen;Y. Kamada;M. Watanabe
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作者：
D. E. Levin;B. Bowers;C. Y. Chen;Y. Kamada;M. Watanabe
芽殖酵母酿酒酵母的PKC 1基因编码细胞生长所必需的哺乳动物PKC的α、β和γ同种型的同源物。PKC 1功能的丧失导致细胞溶解缺陷，其被渗透稳定剂抑制，表明细胞壁完整性缺陷。在这项研究中，我们表明，Pkc 1 p-耗尽的细胞开发孔在其细胞壁定位在其芽尖，该网站的增长是集中在极化细胞生长。这一结果表明pkc 1突变体在生长过程中细胞壁重塑过程中存在缺陷。在进一步支持这一模型，细胞轴承PKC 1 δ突变，允许在渗透稳定剂的存在下增殖，拥有的细胞壁，只有60%的野生型细胞壁厚。细胞壁物质的减少影响了β-葡聚糖层和甘露糖蛋白层。我们已经利用细胞裂解缺陷的PKC 1突变体，以确定在同一信号通路中的PKC 1下游点的功能基因。这些基因包括一个蛋白激酶级联反应，最终激活MAP激酶同源物Mpk 1 p。根据遗传实验，蛋白激酶功能的顺序是Pkc 1 p到Bck 1 p到Mkk 1/2 p到Mpk 1 p。与所提出的模型一致，Pkc 1 p选择性磷酸化Bck 1 p在体外和Mpk 1 p蛋白激酶活性需要一个功能性的BCK 1基因。
The PKC1 gene of the budding yeast Saccharomyces cerevisiae encodes a homolog of the alpha, beta, and gamma isoforms of mammalian PKC that is essential for cell growth. Loss of PKC1 function results in a cell lysis defect that is suppressed by osmotic stabilizing agents, suggesting a defect in cell wall integrity. In this study, we show that Pkc1p-depleted cells develop holes in their cell walls positioned at their bud tips, the site to which growth is focused during polarized cell growth. This result suggests that pkc1 mutants are deficient in the process of cell wall remodeling during growth. In further support of this model, cells bearing a pkc1 delta mutation, allowed to proliferate in the presence of osmotic stabilizing agents, possessed cell walls that were only 60% as thick as wild-type cell walls. This diminution in cell wall material affected both the beta-glucan layer and the mannoprotein layer. We have exploited the cell lysis defect of pkc1 mutants to identify genes that function within the same signalling pathway at points downstream of PKC1. These genes comprise a protein kinase cascade that culminates in the activation of the MAP kinase homolog Mpk1p. The proposed order of protein kinase function, based on genetic experiments, is Pkc1p to Bck1p to Mkk1/2p to Mpk1p. Consistent with the proposed model, Pkc1p selectively phosphorylates Bck1p in vitro and Mpk1p protein kinase activity requires a functional BCK1 gene.