Pim1, a MAP kinase involved in cell wall integrity in Pichia pastoris
Pim1, a MAP kinase involved in cell wall integrity in Pichia pastoris
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DOI：
10.1007/s004380100452
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发表时间：
2001-06-01
影响因子：
3.1
通讯作者：
Molina, M
中科院分区：
文献类型：
--
作者：
Cosano, IC;Martín, H;Molina, M
丝裂原活化蛋白激酶（Mitogen-activated protein kinases，MAPKs）是真核生物信号转导途径中的关键酶。我们报告的分离的毕赤酵母基因，PIM 1，它编码的第一个MAPK被确定在这个酵母。Pim 1与参与维持细胞完整性的真菌MAPK具有最大的相似性。PIM 1基因的破坏导致了一种可修复的热敏性表型，这让人想起在酿酒酵母的MAPK Slt 2/Mpk 1中受影响的突变体中观察到的表型，该突变体参与确保细胞壁的完整性。此外，pim 1突变体对咖啡因和细胞壁不稳定化合物过敏。Pim 1在两个位点被磷酸化，从而响应于热应激、咖啡因和改变真菌细胞壁的试剂而被激活，这与适应这些条件的作用一致。这些结果支持了这样的想法，MAPK为基础的机制，调节细胞壁的完整性是保守的酵母物种。Pim 1在S.在这种酵母中，酵母细胞对激活细胞完整性途径的刺激作出反应。此外，Pim 1能够在单杂交实验中激活报告基因的转录，其S.酿酒酵母对应物，Slt 2.然而，有趣的是，Pim 1不能拯救slt 2 Delta菌株的突变表型。这表明MAPK调节和信号传递的细胞完整性途径的一些功能分歧，并提供了一个工具，可能有助于更好地理解MAPK信号。
Mitogen-activated protein kinases (MAPKs) are key enzymes in the signal transduction pathways of eukaryotes. We report the isolation of a Pichia pastoris gene, PIM1, which encodes the first MAPK to be identified in this yeast. Pim1 shows the greatest similarity to fungal MAPKs involved in the maintenance of cell integrity. Disruption of the PIM1 gene results in an osmoremediable thermosensitive phenotype reminiscent of that observed in mutants affected in the MAPK Slt2/ Mpk1 of Saccharomyces cerevisiae, which is involved in ensuring cell wall integrity. Furthermore, pim1 mutants are hypersensitive to caffeine and cell wall-destabilising compounds. Pim1 is phosphorylated at two sites, and thereby activated, in response to heat stress, caffeine and agents that alter the fungal cell wall, which is consistent with a role in adaptation to these conditions. These results support the idea that the MAPK-based mechanisms which regulate cell wall integrity are conserved in yeast species. Pim1 is alsodoubly phosphorylated in S. cerevisiae in response to stimuli that activate the cell integrity pathway in this yeast. In addition, Pim1 is able to activate the transcription of a reporter gene in one-hybrid experiments, as does its S. cerevisiae counterpart, Slt2. Interestingly, however, Pim1 does not rescue the mutant phenotype of an slt2 Delta strain. This indicates some functional divergence in MAPK modulation and signal transmission by cell integrity pathways and provides a tool that may contribute to a better understanding of MAPK signalling.