MECHANISM OF DNA RECOMBINATION AND REPAIR IN YEAST SACCHAROMYCES CEREVISIAE

DNA聚合酶β被认为是DNA修复所必需的 在哺乳动物细胞中的反应。 尽管其他DNA聚合酶 在酵母和哺乳动物细胞之间功能和结构上保守， 到目前为止，还没有DNA聚合酶β样DNA聚合酶活性被 在酵母细胞中发现。 因此，我们试图鉴定一种新的DNA 聚合酶活性类似于哺乳动物DNA聚合酶β。 我们 在S.酿酒酵母细胞和 部分纯化了这种活性。 虽然它的表观分子量 DNA聚合酶多肽的分子量比DNA聚合酶多肽的分子量大得多。 聚合酶β，它的生化特性非常相似， DNA聚合酶β 为了研究这种新的DNA聚合酶的功能，我们 一直试图用抗体克隆编码DNA聚合酶的基因 针对纯化的DNA聚合酶和PCR技术。 DNA解旋酶被认为不仅是DNA复制所必需的， 也用于DNA修复和重组。 我们已经鉴定并提纯了一种 新的DNA解旋酶活性。 表观分子量和生化 纯化多肽的性质，遗传学研究表明， 这种DNA解旋酶与先前鉴定的DNA 解旋酶，这表明它是由一个新的基因编码。 利用克隆的S.编码DNA链转移的酿酒酵母DST 2 蛋白β作为杂交探针，我们已经确定了两个同源的 DST 2在S.粟球。 其中一个编码120-kDa多肽， 发现是S.粟酒裂殖酵母细胞生长，这表明它 在S.粟球。 使用120-kDa多肽基因作为 作为探针，我们还鉴定并克隆了一个S.酿酒酵母同源物， 编码120-kDa多肽。 就像S。pombe、S.酿酒酵母120-kDa 多肽基因是细胞生长所必需的。 要找到函数的 120-kDa的多肽，我们已经分离出各种温度- 敏感的突变体

It has been believed that DNA polymerase beta is required for DNA repair reaction in mammalian cells. Although other DNA polymerases are well conserved functionally and structurally between yeast and mammalian cells, so far no DNA polymerase beta-like DNA polymerase activity has not been identified in yeast cells. Thus, we have tried to identify a new DNA polymerase activity that resemble to mammalian DNA polymerase beta. We successfully identified in the crude extracts of S. cerevisiae cells and partially purified such activity. Although its apparent molecular weight of the DNA polymerase polypeptide was considerably larger than that of DNA polymerase beta, its biochemical properties were very similar to those of DNA polymerase beta. To study this new DNA polymerase's function, we have been trying to clone a gene encoding the DNA polymerase using antibody against the purified DNA polymerase and the PCR technique. DNA helicase is believed to be required not only for DNA replication, but also for DNA repair and recombination. We have identified and purfied a new DNA helicase activity. The apparent molecular weight and biochemical properties of the purified polypeptide, and genetical studies indicated that this DNA helicase is distinguished from the previously identified DNA helicases in yeast, suggesting that it is encoded by a new gene. Using the cloned S. cerevisiae DST2 which encodes DNA strand transfer protein beta as a hybridization probe, we have identified two homologs of DST2 in S. pombe. One of them which encodes a 120-kDa polypeptide was found to be an essential gene for S. pombe cell growth, suggesting that it plays an important role in S. pombe. Using the 120-kDa polypeptide gene as a probe, we have also identified and cloned a S. cerevisiae homolog which encodes a 120-kDa polypeptide. Like S. pombe, the S. cerevisiae 120-kDa polypeptide gene is essential for cell growth. To find the function of the 120-kDa polypeptide in the cell, we have isolated various temperature- sensitive mutants.