Departamento de Biología Molecular, Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Seville, Spain.
PLoS One. 2013 Jun 7;8(6):e65541. doi: 10.1371/journal.pone.0065541. Print 2013.
To get further insight into the factors involved in the maintenance of genome integrity we performed a screening of Saccharomyces cerevisiae deletion strains inducing hyperrecombination. We have identified trf4, a gene encoding a non-canonical polyA-polymerase involved in RNA surveillance, as a factor that prevents recombination between DNA repeats. We show that trf4Δ confers a transcription-associated recombination phenotype that is mediated by the nascent mRNA. In addition, trf4Δ also leads to an increase in the mutation frequency. Both genetic instability phenotypes can be suppressed by overexpression of RNase H and are exacerbated by overexpression of the human cytidine deaminase AID. These results suggest that in the absence of Trf4 R-loops accumulate co-transcriptionally increasing the recombination and mutation frequencies. Altogether our data indicate that Trf4 is necessary for both mRNA surveillance and maintenance of genome integrity, serving as a link between RNA and DNA metabolism in S. cerevisiae.
为了更深入地了解维持基因组完整性所涉及的因素，我们对诱导高重组的酿酒酵母缺失菌株进行了筛选。我们发现编码非典型聚 A 聚合酶的 trf4 基因是防止 DNA 重复序列之间发生重组的一个因素。我们表明，trf4Δ赋予了一种与转录相关的重组表型，该表型由新生 mRNA 介导。此外，trf4Δ还导致突变频率增加。这两种遗传不稳定性表型都可以通过 RNase H 的过表达来抑制，并且会被人胞嘧啶脱氨酶 AID 的过表达加剧。这些结果表明，在没有 Trf4 的情况下，R 环会在转录过程中积累，从而增加重组和突变频率。总之，我们的数据表明，Trf4 既需要进行 mRNA 监测，又需要维持基因组完整性，是酿酒酵母中 RNA 和 DNA 代谢之间的联系。
