The eukaryotic replisome is rapidly disassembled during DNA replication termination. In metazoa, the cullin-RING ubiquitin ligase CUL-2^LRR-1 drives ubiquitylation of the CMG helicase, leading to replisome disassembly by the p97/CDC-48 “unfoldase”. Here, we combine in vitro reconstitution with in vivo studies in Caenorhabditis elegans embryos, to show that the replisome-associated TIMELESS-TIPIN complex is required for CUL-2^LRR-1 recruitment and efficient CMG helicase ubiquitylation. Aided by TIMELESS-TIPIN, CUL-2^LRR-1 directs a suite of ubiquitylation enzymes to ubiquitylate the MCM-7 subunit of CMG. Subsequently, the UBXN-3 adaptor protein directly stimulates the disassembly of ubiquitylated CMG by CDC-48_UFD-1_NPL-4. We show that UBXN-3 is important in vivo for replisome disassembly in the absence of TIMELESS-TIPIN. Correspondingly, co-depletion of UBXN-3 and TIMELESS causes profound synthetic lethality. Since the human orthologue of UBXN-3, FAF1, is a candidate tumour suppressor, these findings suggest that manipulation of CMG disassembly might be applicable to future strategies for treating human cancer.

中文翻译：

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TIMELESS-TIPIN 和 UBXN-3 在秀丽隐杆线虫 DNA 复制终止过程中促进复制体解体

真核复制体在 DNA 复制终止期间迅速分解。在后生动物中，cullin-RING 泛素连接酶 CUL-2 ^LRR-1驱动 CMG 解旋酶泛素化，导致 p97/CDC-48“解折叠酶”导致复制体分解。在这里，我们将体外重建与秀丽隐杆线虫胚胎的体内研究相结合，表明复制体相关的 TIMELESS-TIPIN 复合物是 CUL-2 ^LRR-1招募和有效的 CMG 解旋酶泛素化所必需的。在 TIMELESS-TIPIN 的帮助下，CUL-2 ^LRR-1指导一套泛素化酶泛素化 CMG 的 MCM-7 亚基。随后，UBXN-3 接头蛋白直接刺激 CDC-48_UFD-1_NPL-4 分解泛素化 CMG。我们证明，在没有 TIMELESS-TIPIN 的情况下，UBXN-3 对于体内复制体分解非常重要。相应地，UBXN-3 和 TIMELESS 的共同消耗会导致严重的合成杀伤力。由于 UBXN-3 的人类直系同源物 FAF1 是一种候选肿瘤抑制因子，因此这些发现表明 CMG 分解的操作可能适用于未来治疗人类癌症的策略。