Song Wei, Dominska Margaret, Greenwell Patricia W, Petes Thomas D
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710.
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710
Proc Natl Acad Sci U S A. 2014 May 27;111(21):E2210-8. doi: 10.1073/pnas.1406847111. Epub 2014 May 5.
In mammalian cells, perturbations in DNA replication result in chromosome breaks in regions termed "fragile sites." Using DNA microarrays, we mapped recombination events and chromosome rearrangements induced by reduced levels of the replicative DNA polymerase-α in the yeast Saccharomyces cerevisiae. We found that the recombination events were nonrandomly associated with a number of structural/sequence motifs that correlate with paused DNA replication forks, including replication-termination sites (TER sites) and binding sites for the helicase Rrm3p. The pattern of gene-conversion events associated with cross-overs suggests that most of the DNA lesions that initiate recombination between homologs are double-stranded DNA breaks induced during S or G2 of the cell cycle, in contrast to spontaneous recombination events that are initiated by double-stranded DNA breaks formed prior to replication. Low levels of DNA polymerase-α also induced very high rates of aneuploidy, as well as chromosome deletions and duplications. Most of the deletions and duplications had Ty retrotransposons at their breakpoints.
在哺乳动物细胞中，DNA复制过程中的扰动会导致在被称为“脆性位点”的区域出现染色体断裂。我们使用DNA微阵列，绘制了酿酒酵母中复制性DNA聚合酶α水平降低所诱导的重组事件和染色体重排图谱。我们发现，重组事件与一些与暂停的DNA复制叉相关的结构/序列基序非随机相关，包括复制终止位点（TER位点）和解旋酶Rrm3p的结合位点。与交叉相关的基因转换事件模式表明，同源物之间启动重组的大多数DNA损伤是在细胞周期的S期或G2期诱导产生的双链DNA断裂，这与在复制前形成双链DNA断裂引发的自发重组事件形成对比。低水平的DNA聚合酶α还诱导了非常高的非整倍体率，以及染色体缺失和重复。大多数缺失和重复在其断点处有Ty反转录转座子。
