MECHANISM OF DNA RECOMBINATION AND REPAIR IN YEAST SACCHAROMYCES CEREVISIAE

一种不依赖ATP的活性，催化一种 从线性双链DNA分子到互补链 已在粗提物中检测到环状单链， 有丝分裂和减数分裂的酵母细胞。 该测定需要 添加酵母单链DNA结合蛋白（ySSB）。 的 多肽（酵母链转移蛋白α ySTP α） 负责这一活动已被纯化到同质， 减数分裂细胞，其特征在于，和抗体提出了从兔子。 使用抗体，ySTP α的基因已经被分离出来， 测定了其核苷酸序列，并对其调控进行了研究。 虽然该基因不是有丝分裂细胞生长所必需的， 是减数分裂同源重组和孢子形成所必需的， 证明ySTP α是减数分裂重组的一种 酵母中的成分和ATP非依赖性反应 在生物学上很重要。 ySTP alpha mRNA和多肽在两个有丝分裂细胞中组成性表达， 和减数分裂酵母细胞。 然而，该多肽是独特的， 在减数分裂过程中被一种机制激活， 鉴定 此外，酵母DNA修复基因之一，RAD18，已经被发现。 克隆，其核苷酸序列已被确定，其 多肽的过量生产和纯化，并研究其调节。

An ATP-independent activity which catalyzes the transfer of one strand from a linear duplex DNA molecule to a complementary circular single strand has been detected in crude extracts from both mitotic and meiotic yeast cells. The assay requires the addition of yeast single-stranded DNA binding protein (ySSB). The polypeptide (yeast Strand Transfer Protein alpha ySTP alpha) responsible for this activity has been purified to homogeneity from meiotic cells, characterized, and antibodies raised from a rabbit. Using the antibodies, the gene for ySTP alpha has been isolated, its nucleotide sequence determined, and its regulation studied. Although the gene is not essential for mitotic cell growth, it is required for meiotic homologous recombination and sporulation, proving that ySTP alpha is one of the meiotic recombination components in yeast and that the ATP-independent reactions catalyzed by ySTP alpha are biologically important. The ySTP alpha mRNA and poly-peptide are constitutively expressed in both mitotic and meiotic Yeast cells. However, the polypeptide is uniquely activated during meiosis by a mechanism that has not yet been identified. In addition, one of the yeast DNA repair genes, RAD18, has been cloned, its nucleotide sequence has been determined, its polypeptide overproduced and purified, and its regulation studied.