INTERMEDIATES OF RECOMBINATION DURING MATING TYPE SWITCHING IN SACCHAROMYCES-CEREVISIAE
INTERMEDIATES OF RECOMBINATION DURING MATING TYPE SWITCHING IN SACCHAROMYCES-CEREVISIAE
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DOI：
10.1002/j.1460-2075.1990.tb08158.x
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发表时间：
1990-03-01
期刊：
影响因子：
11.4
通讯作者：
HABER, JE
中科院分区：
文献类型：
--
作者：
WHITE, CI;HABER, JE
我们已经鉴定了酵母交配型基因同源转换的两个新的中间体，从MATA到MAT.Alpha。在HO内切酶切割后，在HO切割的远端观察到5“到3”的核酸外切消化，产生了一个3“-末端的单链尾巴。这种递归在无法转换的rad52菌株中更为广泛。令人惊讶的是，HO切割的近端辅助序列被保护而不被降解；这种稳定性依赖于沉默的拷贝供体序列的存在。通过聚合酶链式反应(PCR)的定量应用鉴定了第二个中间体。切换产物的Yα-MAT远端共价片段出现在Yα近端的MAT出现前30分钟。交叉口。未检测到MAT远端与HML远端序列的共价连接。我们认为，HO切割末端的MAT DNA侵入了完整的供体，并通过DNA合成而延伸。这一步骤在rad52菌株中是被阻止的。这些中间体与MAT开关模型一致，在该模型中，只有HO切割的远侧最初活跃于链入侵和来自供体的信息转移。
We have identified two novel intermediates of homothallic switching of the yeast mating type gene, from MATa to MAT.alpha.. Following HO endonuclease cleavage, 5'' to 3'' exonucleolytic digestion is observed distal to the HO cut, creating a 3''-ended single-stranded tail. This recision is more extensive in a rad52 strain unable to switch. Surprisingly, the proximal aide of the HO cut is protected from degradation; this stabilization depends on the presence of the silent copy donor sequences. A second intermediate was identified by a quantitative application of the polymerase chain reaction (PCR). The Y.alpha.-MAT distal covalent fragment of the switched product appears 30 min prior to the appearance of the MAT proximal Y.alpha. junction. No covalent joining of MAT distal to HML distal sequences is detected. We suggested that the MAT DNA distal to the HO cut invades the intact donor and is extended by DNA synthesis. This step is prevented in the rad52 strain. These intermediates are consistent with a model for MAT switching in which only the distal side of the HO cut is initially active in strand invasion and transfer of information from the donor.