TIMELESS-TIPIN and UBXN-3 promote replisome disassembly during replication termination in C. elegans

ABSTRACT: The eukaryotic replisome is rapidly disassembled during DNA replication termination. In metazoa, the cullin-RING ubiquitin ligase CUL-2LRR-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 C. elegans embryos, to show that the replisome-associated TIMELESS-TIPIN complex is required for CUL-2LRR-1 recruitment and efficient CMG helicase ubiquitylation. Aided by TIMELESS-TIPIN, CUL-2LRR-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.

SUBMITTER: Prof. Karim Labib 

PROVIDER: S-SCDT-EMBOJ-2021-108053 | biostudies-other |

REPOSITORIES: biostudies-other