Araki H, Hamatake R K, Johnston L H, Sugino A
Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709.
Proc Natl Acad Sci U S A. 1991 Jun 1;88(11):4601-5. doi: 10.1073/pnas.88.11.4601.
The Saccharomyces cerevisiae DNA polymerase II holoenzyme consists of five polypeptides. The largest is the catalytic subunit, whose gene (POL2) has been cloned and sequenced. Herein we describe the cloning and sequencing of DPB2, the gene for the second largest subunit of DNA polymerase II, and the isolation of temperature-sensitive dpb2 mutations. The DNA sequence revealed an open reading frame encoding a protein of Mr 79,461 and lacking significant sequence similarity to any protein in data bases. Disruption of DPB2 was lethal for the cell and the temperature-sensitive dpb2-1 mutant was partially defective in DNA synthesis at the restrictive temperature, indicating that the DPB2 protein is required for normal yeast chromosomal replication. Furthermore, the DNA polymerase II complex was difficult to obtain from dpb2-1 mutant cells, suggesting that a stable DNA polymerase II complex requires DPB2 and is essential for chromosomal replication. The DPB2 transcript periodically fluctuated during the cell cycle and, like those of other genes encoding DNA replication proteins, peaked at the G1/S phase boundary.
酿酒酵母DNA聚合酶II全酶由五种多肽组成。最大的是催化亚基，其基因（POL2）已被克隆和测序。在此我们描述了DPB2的克隆和测序，DPB2是DNA聚合酶II第二大亚基的基因，以及温度敏感型dpb2突变体的分离。DNA序列显示一个开放阅读框，编码一个分子量为79461的蛋白质，且与数据库中的任何蛋白质都没有明显的序列相似性。DPB2的破坏对细胞是致命的，温度敏感型dpb2-1突变体在限制温度下DNA合成存在部分缺陷，这表明DPB2蛋白是正常酵母染色体复制所必需的。此外，很难从dpb2-1突变体细胞中获得DNA聚合酶II复合物，这表明稳定的DNA聚合酶II复合物需要DPB2，并且对染色体复制至关重要。DPB2转录本在细胞周期中周期性波动，并且与其他编码DNA复制蛋白的基因一样，在G1/S期边界达到峰值。
