Differential repair of UV damage in Saccharomyces cerevisiae is cell cycle dependent.
Differential repair of UV damage in Saccharomyces cerevisiae is cell cycle dependent.
复制标题
酿酒酵母中紫外线损伤的差异修复是细胞周期依赖性的。
作者：
C. Terleth;R. Waters;J. Brouwer;P. Putte
在酵母酿酒酵母中，在UV照射后，转录活性MAT α基因座优先于无活性HML α基因座修复。在这里，我们分析了两个位点的修复后，照射酵母细胞在有丝分裂细胞周期的不同阶段。在所有阶段中，活性MAT α位点的修复在60 J/m2的UV剂量后以每小时30%的二聚体去除率发生。在G2中，照射后，无活性的HML α与MAT α一样有效地修复，而在其他阶段，HML α的修复效率较低。因此，在G1和S中观察到差异修复，但在G2中没有。显然，在G2中存在一种染色质结构，其中修复不区分转录活性和失活DNA，或者可能存在一种仅在G2期间起作用的额外修复机制。
In the yeast Saccharomyces cerevisiae the transcriptionally active MAT alpha locus is repaired preferentially to the inactive HML alpha locus after UV irradiation. Here we analysed the repair of both loci after irradiating yeast cells at different stages of the mitotic cell cycle. In all stages repair of the active MAT alpha locus occurs at a rate of 30% removal of dimers per hour after a UV dose of 60 J/m2. The inactive HML alpha is repaired as efficiently as MAT alpha following irradiation in G2 whereas repair of HML alpha is less efficient in the other stages. Thus differential repair is observed in G1 and S but not in G2. Apparently, in G2 a chromatin structure exists in which repair does not discriminate between transcriptionally active and inactive DNA or, alternatively, an additional repair mechanism might exist which is only operational during G2.