Pignède G, Moussy G, Bouvier D, Tillit J, de Recondo A M, Baldacci G
Biologie Moléculaire de la Réplication, UPR 272 CNRS, Villejuif, France.
Chromosoma. 1992;102(1 Suppl):S128-32. doi: 10.1007/BF02451796.
This paper reports on expression and posttranslational modifications of the catalytic subunits of pol alpha and pol delta from fission yeast Schizosaccharomyces pombe. Okadaic acid treatment of S. pombe spheroplasts in amounts known to inhibit phosphatases 1 and 2A resulted in decreased proteolysis of both pol alpha and pol delta. Computer analysis of pol alpha and pol delta sequences confirmed the presence of consensus motifs for protein phosphorylation. Indirect immunofluorescence microscopy of S. pombe cells showed nuclear location of both proteins in wild type cells. However, whereas cells transformed with a vector expressing pol alpha produced a clear increase of the nuclear signal, no increase was detectable in cells transformed with pol delta. This observation suggests the existence of a mechanism limiting the cell concentration of pol delta in the cell. Constitutive expression of S. pombe pol delta in E. coli was possible only with vectors containing truncated forms of its gene, indicating a toxic effect of pol delta on E. coli growth.
本文报道了裂殖酵母粟酒裂殖酵母中DNA聚合酶α和DNA聚合酶δ催化亚基的表达及翻译后修饰。用已知可抑制磷酸酶1和2A的量的冈田酸处理粟酒裂殖酵母原生质体，导致DNA聚合酶α和DNA聚合酶δ的蛋白水解减少。对DNA聚合酶α和DNA聚合酶δ序列的计算机分析证实了蛋白质磷酸化共有基序的存在。粟酒裂殖酵母细胞的间接免疫荧光显微镜检查显示，在野生型细胞中这两种蛋白质都定位于细胞核。然而，用表达DNA聚合酶α的载体转化的细胞中，核信号明显增加，而用DNA聚合酶δ转化的细胞中未检测到增加。这一观察结果表明存在一种限制细胞中DNA聚合酶δ细胞浓度的机制。只有用含有其基因截短形式的载体才能在大肠杆菌中组成型表达粟酒裂殖酵母DNA聚合酶δ，这表明DNA聚合酶δ对大肠杆菌生长具有毒性作用。
