Shimanuki M, Kinoshita N, Ohkura H, Yoshida T, Toda T, Yanagida M
Department of Biophysics, Faculty of Science, Kyoto University, Japan.
Mol Biol Cell. 1993 Mar;4(3):303-13. doi: 10.1091/mbc.4.3.303.
We isolated a fission yeast putative protein serine/threonine phosphatase gene designated ppe1+ by hybridization. The predicted amino acid sequence is similar to those of the fission yeast ppa2 (53% identity) and dis2 (39%) phosphatases, and highly similar to those of the budding yeast SIT4 (72%), Drosophila PPV (68%) and rabbit PPX (61%) phosphatases. Antibodies against ppe1 protein identified a 37-kd polypeptide in fission yeast. A gene disruption (designated delta ppe1) caused cold-sensitive lethality and short, pear-shaped cells. These phenotypes were fully suppressed by a plasmid carrying ppe1+. Three classes of multicopy suppressor genes for delta ppe1 were identified as follows: 1) ppa1+ and ppa2+ encoding type 2A-like phosphatases, 2) mitotically essential dis3+ similar to the budding yeast SSD1/SRK1, a suppressor for sit4, and 3) pck1+ coding for a protein kinase C-like kinase. Consistently, the budding yeast SIT4 gene was also a multicopy suppressor for delta ppe1. Phosphatase ppe1 may play a role in cell morphogenesis and mitosis by either regulating or being regulated by these multicopy suppressor gene products. Consistent with this hypothesis, double mutants ppe1-ppa2 and ppe1-pck1 are lethal at the permissive temperature.
我们通过杂交分离出一个裂殖酵母假定的蛋白丝氨酸/苏氨酸磷酸酶基因，命名为ppe1+。预测的氨基酸序列与裂殖酵母ppa2（同一性为53%）和dis2（39%）磷酸酶的序列相似，与芽殖酵母SIT4（72%）、果蝇PPV（68%）和兔PPX（61%）磷酸酶的序列高度相似。针对ppe1蛋白的抗体在裂殖酵母中鉴定出一条37-kd的多肽。基因破坏（命名为delta ppe1）导致冷敏感致死性以及短小的梨形细胞。这些表型被携带ppe1+的质粒完全抑制。鉴定出三类delta ppe1的多拷贝抑制基因如下：1）编码2A类磷酸酶的ppa1+和ppa2+，2）与芽殖酵母SSD1/SRK1相似的有丝分裂必需的dis3+，sit4的一个抑制子，以及3）编码蛋白激酶C样激酶的pck1+。同样，芽殖酵母SIT4基因也是delta ppe1的多拷贝抑制子。磷酸酶ppe1可能通过调节这些多拷贝抑制基因产物或被其调节，在细胞形态发生和有丝分裂中发挥作用。与这一假设一致，ppe1-ppa2和ppe1-pck1双突变体在允许温度下是致死的。
