MECHANISM OF DNA RECOMBINATION AND REPAIR IN YEAST SACCHAROMYCES CEREVISIAE

与单链DNA结合的蛋白质有望 参与DNA复制、重组和修复。 几种单链DNA结合蛋白(SSB)(14KD， 20kD、26KD、35kD、38KD、42KD和45KD 来自酵母的酿酒酵母和抗体 被提出来反对他们。使用抗体作为探针， SSB基因已被鉴定和测序。删除和/或 这些基因的中断已经被构建，并且 由此产生的表型被研究。至少20KD的SSB基因是 对细胞存活至关重要。 一种不依赖于三磷酸腺苷的活性，催化一种 从DNA的双链线性分子到一个 在原油中检测到互补的圆形单链 通过添加酵母SSB从有丝分裂和减数分裂细胞中提取。 这种活性在减数分裂过程中增加了15倍以上 MATAlpha/MATAlpha二倍体，但两者都不是 MATAlpha/MATAlpha或MATAlpha/MATAlpha。多肽 负责这一活动的人被提纯为同质 减数分裂细胞和特征。尽管这条酵母链- 交换蛋白(YSEP)的性质类似于 原核生物SEPS和一些真核SEPS，是不同的 因为它不需要核苷酸辅因子，所以它的反应是 高效、快速、催化量的蛋白质是 反应所必需的。这种减数分裂的ySEP活性是 受RAD50和RAD52基因控制，这是必需的 用于减数分裂重组和产孢子。两者都有 单克隆性和单特异性多克隆抗体已经被 针对同质ySEP和身份验证提出 该基因的克隆工作正在进行中。

Proteins binding to single-stranded DNA are expected to participate in DNA replication, recombination and repair. Several single-stranded DNA binding proteins (SSBs) (14KD, 20KD, 26KD, 35KD, 38KD, 42KD and 45KD) have been purified from the yeast Saccharomyces cerevisiae and antibodies have been raised against them. Using the antibodies as probes, the SSB genes have been identified and sequenced. Deletions and/or disruptions of these genes have been constructed and the resulting phenotypes studied. At least the 20KD SSB gene is essential for cell viability. An ATP-independent activity that catalyzes the transfer of one strand from a duplex linear molecule of DNA to a complementary circular single strand has been detected in crude extracts from mitotic and meiotic cells by adding yeast SSBs. This activity increases more than 15-fold during meiosis in MATalpha/MATalpha diploids, but not in neither MATalpha/MATalpha or MATalpha/MATalpha. The polypeptide responsible for this activity was purified to homogeneity from meiotic cells and characterized. Although this yeast strand- exchange protein (ySEP) has properties similar to those of prokaryotic SEPs and some eucaryotic SEPs, it is distinct because it requires no nucleotide cofactor, its reaction is efficient and rapid, and catalytic amounts of the protein are required for the reaction. This meiotic ySEP activity is controlled by the RAD50 and RAD52 genes which are required for meiotic recombination as well as sporulation. Both monoclonal and monospecific polyclonal antibodies have been raised against the homogeneous ySEP and identification and cloning of the gene are underway.