González-Barrera Sergio, García-Rubio María, Aguilera Andrés
Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Spain.
Genetics. 2002 Oct;162(2):603-14. doi: 10.1093/genetics/162.2.603.
We have made a comparative analysis of double-strand-break (DSB)-induced recombination and spontaneous recombination under low- and high-transcription conditions in yeast. We constructed two different recombination substrates, one for the analysis of intermolecular gene conversions and the other for intramolecular gene conversions and inversions. Such substrates were based on the same leu2-HOr allele fused to the tet promoter and containing a 21-bp HO site. Gene conversions and inversions were differently affected by rad1, rad51, rad52, and rad59 single and double mutations, consistent with the actual view that such events occur by different recombination mechanisms. However, the effect of each mutation on each type of recombination event was the same, whether associated with transcription or induced by the HO-mediated DSB. Both the highly transcribed DNA and the HO-cut sequence acted as recipients of the gene conversion events. These results are consistent with the hypothesis that transcription promotes initiation of recombination along the DNA sequence being transcribed. The similarity between transcription-associated and DSB-induced recombination suggests that transcription promotes DNA breaks.
我们对酵母中低转录和高转录条件下双链断裂(DSB)诱导的重组与自发重组进行了比较分析。我们构建了两种不同的重组底物,一种用于分析分子间基因转换,另一种用于分析分子内基因转换和倒位。此类底物基于与tet启动子融合且含有21bp HO位点的相同leu2 - HOr等位基因。基因转换和倒位受rad1、rad51、rad52和rad59单突变及双突变的影响不同,这与这些事件通过不同重组机制发生的实际观点一致。然而,无论与转录相关还是由HO介导的DSB诱导,每个突变对每种重组事件类型的影响都是相同的。高度转录的DNA和HO切割序列均作为基因转换事件的受体。这些结果与转录促进沿转录DNA序列的重组起始这一假设一致。转录相关重组与DSB诱导重组之间的相似性表明转录促进DNA断裂。