Ohya Tomoko, Kawasaki Yasuo, Hiraga Shin-Ichiro, Kanbara Sakie, Nakajo Kou, Nakashima Naomi, Suzuki Akiko, Sugino Akio
Department of Biochemistry and Molecular Biology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
J Biol Chem. 2002 Aug 2;277(31):28099-108. doi: 10.1074/jbc.M111573200. Epub 2002 May 15.
Saccharomyces cerevisiae POL2 encodes the catalytic subunit of DNA polymerase epsilon. This study investigates the cellular functions performed by the polymerase domain of Pol2p and its role in DNA metabolism. The pol2-16 mutation has a deletion in the catalytic domain of DNA polymerase epsilon that eliminates its polymerase and exonuclease activities. It is a viable mutant, which displays temperature sensitivity for growth and a defect in elongation step of chromosomal DNA replication even at permissive temperatures. This mutation is synthetic lethal in combination with temperature-sensitive mutants or the 3'- to 5'-exonuclease-deficient mutant of DNA polymerase delta in a haploid cell. These results suggest that the catalytic activity of DNA polymerase epsilon participates in the same pathway as DNA polymerase delta, and this is consistent with the observation that DNA polymerases delta and epsilon colocalize in some punctate foci on yeast chromatids during S phase. The pol2-16 mutant senesces more rapidly than wild type strain and also has shorter telomeres. These results indicate that the DNA polymerase domain of Pol2p is required for rapid, efficient, and highly accurate chromosomal DNA replication in yeast.
酿酒酵母POL2编码DNA聚合酶ε的催化亚基。本研究调查了Pol2p聚合酶结构域所执行的细胞功能及其在DNA代谢中的作用。pol2-16突变在DNA聚合酶ε的催化结构域中有一个缺失，消除了其聚合酶和核酸外切酶活性。它是一个存活突变体，对生长表现出温度敏感性，即使在允许温度下，染色体DNA复制的延伸步骤也存在缺陷。在单倍体细胞中，该突变与温度敏感突变体或DNA聚合酶δ的3'至5'核酸外切酶缺陷突变体组合时是合成致死的。这些结果表明，DNA聚合酶ε的催化活性与DNA聚合酶δ参与相同的途径，这与在S期DNA聚合酶δ和ε共定位于酵母染色单体上的一些点状病灶的观察结果一致。pol2-16突变体比野生型菌株衰老更快，端粒也更短。这些结果表明，Pol2p的DNA聚合酶结构域是酵母中快速、高效和高度准确的染色体DNA复制所必需的。
