Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
Genetics. 2012 Sep;192(1):147-60. doi: 10.1534/genetics.112.141051. Epub 2012 Jun 5.
Genetic screens of the collection of ~4500 deletion mutants in Saccharomyces cerevisiae have identified the cohort of nonessential genes that promote maintenance of genome integrity. Here we probe the role of essential genes needed for genome stability. To this end, we screened 217 tetracycline-regulated promoter alleles of essential genes and identified 47 genes whose depletion results in spontaneous DNA damage. We further showed that 92 of these 217 essential genes have a role in suppressing chromosome rearrangements. We identified a core set of 15 genes involved in DNA replication that are critical in preventing both spontaneous DNA damage and genome rearrangements. Mapping, classification, and analysis of rearrangement breakpoints indicated that yeast fragile sites, Ty retrotransposons, tRNA genes, early origins of replication, and replication termination sites are common features at breakpoints when essential replication genes that suppress chromosome rearrangements are downregulated. We propose mechanisms by which depletion of essential replication proteins can lead to double-stranded DNA breaks near these features, which are subsequently repaired by homologous recombination at repeated elements.
酵母约 4500 个缺失突变体的遗传筛选已经鉴定出促进基因组完整性维持的非必需基因群。在这里,我们探讨了维持基因组稳定性所必需的基因的作用。为此,我们筛选了 217 个四环素调控的必需基因启动子等位基因,发现了 47 个基因缺失会导致自发 DNA 损伤。我们进一步表明,这 217 个必需基因中的 92 个在抑制染色体重排方面发挥作用。我们确定了一个核心的 15 个与 DNA 复制有关的基因,这些基因在防止自发 DNA 损伤和基因组重排方面至关重要。重排断点的定位、分类和分析表明,当抑制染色体重排的必需复制基因下调时,酵母脆性位点、Ty 反转录转座子、tRNA 基因、早期复制起点和复制终止位点是断点的常见特征。我们提出了这样一种机制,即必需复制蛋白的缺失会导致这些特征附近双链 DNA 断裂,随后通过同源重组在重复元件处修复。