RECQ5 Helicase Cooperates with MUS81 Endonuclease in Processing Stalled Replication Forks at Common Fragile Sites during Mitosis

• Published in: Molecular cell Vol. 66; no. 5; pp. 658 - 671.e8
• Main Authors: Di Marco, Stefano, Hasanova, Zdenka, Kanagaraj, Radhakrishnan, Chappidi, Nagaraja, Altmannova, Veronika, Menon, Shruti, Sedlackova, Hana, Langhoff, Jana, Surendranath, Kalpana, Hühn, Daniela, Bhowmick, Rahul, Marini, Victoria, Ferrari, Stefano, Hickson, Ian D., Krejci, Lumir, Janscak, Pavel
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.06.2017
• Subjects: Binding Sites; CDC2 Protein Kinase; Chromosomal Instability; Chromosome Fragile Sites; Chromosome Segregation; common fragile sites; Cyclin-Dependent Kinases - metabolism; DNA - biosynthesis; DNA - genetics; DNA Damage; DNA Repair; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Endodeoxyribonucleases - metabolism; Endonucleases - genetics; Endonucleases - metabolism; genomic instability; HEK293 Cells; HeLa Cells; Humans; Mitosis; mitotic DNA synthesis; MUS81; Phosphorylation; Protein Binding; RAD51 filament; Rad51 Recombinase - metabolism; RecQ Helicases - genetics; RecQ Helicases - metabolism; RECQ5; Replication Origin; replication stress; RNA Interference; Time Factors; Transfection; MUS81; replication stress; common fragile sites; RAD51 filament; RECQ5; mitotic DNA synthesis; genomic instability
• ISSN: 1097-2765; 1097-4164
• DOI: 10.1016/j.molcel.2017.05.006

The MUS81-EME1 endonuclease cleaves late replication intermediates at common fragile sites (CFSs) during early mitosis to trigger DNA-repair synthesis that ensures faithful chromosome segregation. Here, we show that these DNA transactions are promoted by RECQ5 DNA helicase in a manner dependent on its Ser727 phosphorylation by CDK1. Upon replication stress, RECQ5 associates with CFSs in early mitosis through its physical interaction with MUS81 and promotes MUS81-dependent mitotic DNA synthesis. RECQ5 depletion or mutational inactivation of its ATP-binding site, RAD51-interacting domain, or phosphorylation site causes excessive binding of RAD51 to CFS loci and impairs CFS expression. This leads to defective chromosome segregation and accumulation of CFS-associated DNA damage in G1 cells. Biochemically, RECQ5 alleviates the inhibitory effect of RAD51 on 3′-flap DNA cleavage by MUS81-EME1 through its RAD51 filament disruption activity. These data suggest that RECQ5 removes RAD51 filaments stabilizing stalled replication forks at CFSs and hence facilitates CFS cleavage by MUS81-EME1. [Display omitted] •RECQ5 binds to and stimulates MUS81-EME1 endonuclease•RECQ5 promotes mitotic DNA synthesis (MiDAS) at CFSs•RECQ5 removes RAD51 filaments protecting stalled replication forks at CFSs•Expression of CFSs depends on RECQ5 phosphorylation by CDK1 MUS81-EME1 endonuclease cleaves late replication intermediates at common fragile sites in early mitosis to trigger DNA-repair synthesis, ensuring faithful chromosome segregation. Di Marco et al. show that RECQ5 eliminates RAD51 filaments from these structures to facilitate the access of MUS81-EME1 to DNA.