Vance John R, Wilson Thomas E
Plantaceutica, Incorporated, P.O. Box 12060, 99 Alexander Drive, Research Triangle Park, NC 27709-2060, USA.
Proc Natl Acad Sci U S A. 2002 Oct 15;99(21):13669-74. doi: 10.1073/pnas.202242599. Epub 2002 Oct 4.
When a replication fork collides with a DNA topoisomerase I (Top1) cleavage complex, the covalently bound enzyme must be removed from the DNA 3' end before recombination-dependent replication restart. Here we report that the tyrosyl-DNA phosphodiesterase Tdp1 and the structure-specific endonuclease Rad1-Rad10 function as primary alternative pathways of Top1 repair in Saccharomyces cerevisiae. Thus, tdp1 rad1 cells (including the catalytic point mutant rad1-D869A) not only are highly sensitive to the Top1 poison camptothecin but also exhibit a TOP1-dependent growth delay. Extensive genetic analysis revealed that both Tdp1 and Rad1-Rad10 repair proceed through recombination that equally depends on RAD52, RAD51, and RAD50. The Rad1-Rad10 pathway further particularly depends on RAD59 and SRS2 but is independent of other nucleotide excision repair genes. Although this pattern is consistent with Rad1-Rad10 removing Top1 in a manner similar to its removal of nonhomologous tails during gene conversion, these differ in that Top1 removal does not require Msh2-Msh3. Finally, we show that yeast lacking the Rad1-Rad10-related proteins Mus81-Mms4 display a unique pattern of camptothecin sensitivity and suggest a concerted model for the action of these endonucleases.
当复制叉与DNA拓扑异构酶I（Top1）切割复合物碰撞时，在依赖重组的复制重新启动之前，必须从DNA 3'末端去除共价结合的酶。在此，我们报道酪氨酰-DNA磷酸二酯酶Tdp1和结构特异性核酸内切酶Rad1-Rad10在酿酒酵母中作为Top1修复的主要替代途径发挥作用。因此，tdp1 rad1细胞（包括催化点突变体rad1-D869A）不仅对Top1毒素喜树碱高度敏感，而且表现出依赖TOP1的生长延迟。广泛的遗传分析表明，Tdp1和Rad1-Rad10修复均通过重组进行，同样依赖于RAD52、RAD51和RAD50。Rad1-Rad10途径进一步特别依赖于RAD59和SRS2，但不依赖于其他核苷酸切除修复基因。虽然这种模式与Rad1-Rad10以类似于其在基因转换过程中去除非同源尾巴的方式去除Top1一致，但这些不同之处在于，去除Top1不需要Msh2-Msh3。最后，我们表明缺乏Rad1-Rad10相关蛋白Mus81-Mms4的酵母表现出独特的喜树碱敏感性模式，并提出了这些核酸内切酶作用的协同模型。
