Fortunato E A, Osman F, Subramani S
Department of Biology, University of California San Diego, La Jolla 92093-0322, USA.
Mutat Res. 1996 Dec 2;364(3):14-60.
Schizosaccharomyces pombe strains containing direct repeats of adeó heteroalleles separated by a functional uro4+ gene, and a DNA site for induction of a double-strand break (DSB), have been used to analyze pathways of spontaneous and DSB-induced intrachromosomal mitotic recombination. These substrates yield Ade+ Ura+ convertants or Ade+ Ura- deletions, by the DSB/gap repair and single-strand annealing (SSA) pathways of recombination, respectively. In S. cerevisiae, the DSB/gap repair pathway is RAD52 dependent, and the RAD1 and RAD10 genes are involved in the SSA pathway. We have sought to understand the genetic control of the pathways of mitotic recombination in S. pombe by determining the effects of mutations in six rad genes involved in DNA repair: rad1 and rad3 involved in checkpoint control in response to unreplicated or damaged DNA; rad5 (homologue of S. cerevisiae RAD3) and rad10 (homologue of S. cerevisiae RAD1) involved in nucleotide excision repair; rad21 and rad22 (homologue of S. cerevisiae RAD52) involved in the repair of ionizing radiation-induced DNA damage. The results suggest that the genetic control of the pathways of spontaneous and DSB-induced mitotic intrachromosomal recombination in S. pombe is different from that in S. cerevisiae.
含有由功能性ura4⁺基因隔开的ade6杂合等位基因直接重复序列以及双链断裂（DSB）诱导DNA位点的粟酒裂殖酵母菌株，已被用于分析自发的和DSB诱导的染色体内有丝分裂重组途径。这些底物分别通过DSB/缺口修复和单链退火（SSA）重组途径产生Ade⁺Ura⁺转化体或Ade⁺Ura⁻缺失体。在酿酒酵母中，DSB/缺口修复途径依赖于RAD52，而RAD1和RAD10基因参与SSA途径。我们试图通过确定参与DNA修复的六个rad基因中的突变效应，来了解粟酒裂殖酵母中有丝分裂重组途径的遗传控制：rad1和rad3参与对未复制或受损DNA的检查点控制；rad5（酿酒酵母RAD3的同源物）和rad10（酿酒酵母RAD1的同源物）参与核苷酸切除修复；rad21和rad22（酿酒酵母RAD52的同源物）参与电离辐射诱导的DNA损伤修复。结果表明，粟酒裂殖酵母中自发的和DSB诱导的染色体内有丝分裂重组途径的遗传控制与酿酒酵母不同。
