Centre National de la Recherche Scientifique, UMR8226, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, Institut de Biologie Physico-Chimique, 75005 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR8226, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, Institut de Biologie Physico-Chimique, 75005 Paris, France.
Centre National de la Recherche Scientifique, UMR8226, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, Institut de Biologie Physico-Chimique, 75005 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR8226, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, Institut de Biologie Physico-Chimique, 75005 Paris, France.
Mol Cell. 2014 Mar 20;53(6):954-64. doi: 10.1016/j.molcel.2014.02.030.
The model for telomere shortening at each replication cycle is currently incomplete, and the exact contribution of the telomeric 3' overhang to the shortening rate remains unclear. Here, we demonstrate key steps of the mechanism of telomere replication in Saccharomyces cerevisiae. By following the dynamics of telomeres during replication at near-nucleotide resolution, we find that the leading-strand synthesis generates blunt-end intermediates before being 5'-resected and filled in. Importantly, the shortening rate is set by positioning the last Okazaki fragments at the very ends of the chromosome. Thus, telomeres shorten in direct proportion to the 3' overhang lengths of 5-10 nucleotides that are present in parental templates. Furthermore, the telomeric protein Cdc13 coordinates leading- and lagging-strand syntheses. Taken together, our data unravel a precise choreography of telomere replication elucidating the DNA end-replication problem and provide a framework to understand the control of the cell proliferation potential.
目前，端粒在每个复制循环中缩短的模型并不完整，端粒 3'突出端对缩短率的确切贡献仍不清楚。在这里，我们展示了酿酒酵母中端粒复制机制的关键步骤。通过在接近核苷酸分辨率的情况下跟踪复制过程中端粒的动态，我们发现前导链合成在 5'切除和填补之前产生了钝端中间体。重要的是，通过将最后一个冈崎片段定位在染色体的末端，确定了缩短率。因此，端粒的缩短与存在于亲本模板中的 5-10 个核苷酸的 3'突出端长度成正比。此外，端粒蛋白 Cdc13 协调前导链和滞后链的合成。总之，我们的数据揭示了端粒复制的精确编排，阐明了 DNA 末端复制问题，并为理解细胞增殖潜力的控制提供了一个框架。
