Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, 1050 Childs Way, Los Angeles, CA 90089-2910, USA.
Genes (Basel). 2022 Nov 24;13(12):2202. doi: 10.3390/genes13122202.
Eukaryotic genomes are replicated in spatiotemporal patterns that are stereotypical for individual genomes and developmental profiles. In the model system , two primary mechanisms determine the preferential activation of replication origins during early S phase, thereby largely defining the consequent replication profiles of these cells. Both mechanisms are thought to act through specific recruitment of a rate-limiting initiation factor, Dbf4-dependent kinase (DDK), to a subset of licensed replication origins. Fkh1/2 is responsible for stimulation of most early-firing origins, except for centromere (CEN)-proximal origins that recruit DDK via the kinetochore protein Ctf19, which is required for their early firing. The C-terminus of Dbf4 has been implicated in its recruitment to origins via both the Fkh1/2 and Ctf19 mechanisms. Here, we show that the Zn-finger motif within the C-terminus is specifically required for Dbf4 recruitment to CENs to stimulate CEN-proximal/Ctf19-dependent origins, whereas stimulation of origins via the Fkh1/2 pathway remains largely intact. These findings re-open the question of exactly how Fkh1/2 and DDK act together to stimulate replication origin initiation.
真核基因组以时空模式复制，这种模式对于个体基因组和发育特征是典型的。在模型系统中，两种主要机制决定了复制起点在早期 S 期的优先激活，从而在很大程度上定义了这些细胞的后续复制特征。这两种机制都被认为是通过特定的招募限速起始因子 Dbf4 依赖性激酶（DDK）来发挥作用的，该激酶被招募到一组许可的复制起点上。Fkh1/2 负责刺激大多数早期起始的复制起点，但不包括着丝粒（CEN）近端的复制起点，这些复制起点通过动粒蛋白 Ctf19 招募 DDK，这对于它们的早期激活是必需的。Dbf4 的 C 端被认为参与了其通过 Fkh1/2 和 Ctf19 机制招募到复制起点。在这里，我们表明 C 端的锌指结构域对于 Dbf4 招募到着丝粒以刺激着丝粒近端/ Ctf19 依赖的复制起点是特异性必需的，而通过 Fkh1/2 途径刺激复制起点的功能则基本完整。这些发现重新提出了 Fkh1/2 和 DDK 如何共同作用来刺激复制起点起始的确切问题。
