Luke Brian, Versini Gwennaelle, Jaquenoud Malika, Zaidi Iram Waris, Kurz Thimo, Pintard Lionel, Pasero Philippe, Peter Matthias
Swiss Federal Institute of Technology Zurich (ETH), Institute of Biochemistry, ETH Hoenggerberg HPM G 10.0, Switzerland.
Curr Biol. 2006 Apr 18;16(8):786-92. doi: 10.1016/j.cub.2006.02.071.
Accurate and complete DNA replication is fundamental to maintain genome integrity. While the mechanisms and underlying machinery required to duplicate bulk genomic DNA are beginning to emerge, little is known about how cells replicate through damaged areas and special chromosomal regions such as telomeres, centromeres, and highly transcribed loci . Here, we have investigated the role of the yeast cullin Rtt101p in this process. We show that rtt101Delta cells accumulate spontaneous DNA damage and exhibit a G(2)/M delay, even though they are fully proficient to detect and repair chromosome breaks. Viability of rtt101Delta mutants depends on Rrm3p, a DNA helicase involved in displacing proteinaceous complexes at programmed pause sites . Moreover, rtt101Delta cells show hyperrecombination at forks arrested at replication fork barriers (RFBs) of ribosomal DNA. Finally, rtt101Delta mutants are sensitive to fork arrest induced by DNA alkylation, but not by nucleotide depletion. We therefore propose that the cullin Rtt101p promotes fork progression through obstacles such as DNA lesions or tightly bound protein-DNA complexes via a new mechanism involving ubiquitin-conjugation.
准确而完整的DNA复制对于维持基因组完整性至关重要。虽然复制大量基因组DNA所需的机制和潜在机制已初现端倪，但对于细胞如何通过受损区域以及端粒、着丝粒和高度转录位点等特殊染色体区域进行复制却知之甚少。在此，我们研究了酵母cullin蛋白Rtt101p在此过程中的作用。我们发现，rtt101Δ细胞会积累自发的DNA损伤并表现出G2/M期延迟，尽管它们完全能够检测和修复染色体断裂。rtt101Δ突变体的生存能力取决于Rrm3p，一种参与在程序性暂停位点置换蛋白质复合物的DNA解旋酶。此外，rtt101Δ细胞在核糖体DNA的复制叉屏障（RFB）处停滞的复制叉处表现出高度重组。最后，rtt101Δ突变体对DNA烷基化诱导的复制叉停滞敏感，但对核苷酸耗竭诱导的停滞不敏感。因此，我们提出cullin蛋白Rtt101p通过一种涉及泛素缀合的新机制促进复制叉通过诸如DNA损伤或紧密结合的蛋白质-DNA复合物等障碍。
