Lemoine Francene J, Degtyareva Natasha P, Lobachev Kirill, Petes Thomas D
Department of Biology and Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Cell. 2005 Mar 11;120(5):587-98. doi: 10.1016/j.cell.2004.12.039.
In the yeast Saccharomyces cerevisiae, reduced levels of the replicative alpha DNA polymerase result in greatly elevated frequencies of chromosome translocations and chromosome loss. We selected translocations in a small region of chromosome III and found that they involve homologous recombination events between yeast retrotransposons (Ty elements) on chromosome III and retrotransposons located on other chromosomes. One of the two preferred sites of these translocations on chromosome III involve two Ty elements arrayed head-to-head; disruption of this site substantially reduces the rate of translocations. We demonstrate that this pair of Ty elements constitutes a preferred site for double-strand DNA breaks when DNA replication is compromised, analogous to the fragile sites observed in mammalian chromosomes.
在酿酒酵母中，复制性α DNA聚合酶水平降低会导致染色体易位和染色体丢失的频率大幅升高。我们在第三条染色体的一个小区域内选择了易位事件，发现它们涉及第三条染色体上的酵母逆转录转座子（Ty元件）与位于其他染色体上的逆转录转座子之间的同源重组事件。这些易位在第三条染色体上的两个优先位点之一涉及两个首尾相连排列的Ty元件；破坏这个位点会大幅降低易位率。我们证明，当DNA复制受损时，这对Ty元件构成双链DNA断裂的优先位点，类似于在哺乳动物染色体中观察到的脆性位点。
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