A mitotic role for a novel fission yeast protein kinase dsk1 with cell cycle stage dependent phosphorylation and localization.
A mitotic role for a novel fission yeast protein kinase dsk1 with cell cycle stage dependent phosphorylation and localization.
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DOI：
10.1091/mbc.4.3.247
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发表时间：
1993-03
影响因子：
3.3
通讯作者：
Masahiro Takeuchi;M. Yanagida
中科院分区：
文献类型：
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作者：
Masahiro Takeuchi;M. Yanagida
裂殖酵母dsk 1+基因是冷敏感dis 1突变体的多拷贝抑制基因，编码一种新的61 kd蛋白激酶。它是一种磷蛋白，磷酸丝氨酸是主要的磷酸化氨基酸。dsk 1的过度磷酸化导致迁移率改变，导致两个dsk 1特异性蛋白条带。当细胞周期进程延迟或停滞时，磷酸化模式发生显著改变。缓慢迁移的磷酸化形式在有丝分裂阻滞的细胞中很突出，而快速迁移的形式在间期阻滞的细胞中很丰富。DSK 1是一种蛋白激酶。它自身磷酸化以及磷酸化髓鞘碱性蛋白（MBP）。磷酸酪氨酸以及磷酸丝氨酸/苏氨酸被发现在自磷酸化，但没有酪氨酸磷酸化发生时，MBP作为底物。有丝分裂阻滞细胞的dsk 1免疫沉淀物具有比野生型高几倍的激酶活性。单倍体基因破坏物是可行的，这表明dsk 1+基因是非必需的生存能力。而高剂量的dsk 1+可明显延缓G2/M期进展。使用抗-dsk 1抗体的免疫荧光显微镜显示，dsk 1蛋白的定位模式根据细胞周期阶段而显著改变。在G2期阻滞的细胞中，dsk 1定位于细胞质中，而在有丝分裂阻滞的细胞中，核染色强烈。在野生型细胞中，核染色仅见于有丝分裂细胞。因此，dsk 1蛋白可能通过改变细胞位置、磷酸化程度和激酶活性在有丝分裂控制中发挥重要作用。我们讨论了dsk 1激酶作为一个附加的有丝分裂调节剂的可能作用。
The fission yeast dsk1+ gene, a multicopy suppressor for cold-sensitive dis1 mutants, encodes a novel 61-kd protein kinase. It is a phosphoprotein, and phosphoserine is the major phosphorylated amino acid. Hyperphosphorylation of dsk1 causes a mobility shift, resulting in two dsk1-specific protein bands. The phosphorylation pattern is strikingly altered when cell cycle progression is delayed or arrested. The slowly migrating phosphorylated form is prominent in mitotically arrested cells, and the fast migrating form is enriched in interphase-arrested cells. dsk1 is a protein kinase. It auto-phosphorylates as well as phosphorylates myelin basic protein (MBP). Phosphotyrosine as well as phosphoserine/threonine were found in autophosphorylation, but no tyrosine phosphorylation occurs when MBP was used as the substrate. The dsk1 immunoprecipitates from mitotically arrested cells have a several-fold higher kinase activity than that from wild type. The haploid gene disruptant is viable, indicating that the dsk1+ gene is non-essential for viability. High dosage of dsk1+, however, strongly delays the G2/M progression. Immunofluorescence microscopy using anti-dsk1 antibody shows that localization pattern of dsk1 protein strikingly alters depending on cell cycle stages. In G2-arrested cells, dsk1 locates in the cytoplasm, whereas in mitotically arrested cells, nuclear stain is intense. In wild-type cells, nuclear stain is seen only in mitotic cells. Hence dsk1 protein may play an important role in mitotic control by altering cellular location, degree of phosphorylation and kinase activity. We discuss possible roles of dsk1 kinase as an add-on regulator in mitosis.