FANCJ DNA helicase is recruited to the replisome by AND-1 to ensure genome stability

Abstract

FANCJ is a DNA helicase linked to Fanconi anemia and frequently mutated in breast and ovarian cancers. If and how FANCJ is recruited to the replisome is unknown. Here, we report that FANCJ directly binds to AND-1 (the vertebrate ortholog of budding yeast Ctf4), a homo-trimeric protein adaptor that connects the CDC45/MCM2-7/GINS replicative DNA helicase with DNA polymerase and several factors at DNA replication forks. We find that the interaction between FANCJ and AND-1 requires the integrity of an evolutionarily conserved Ctf4-interacting protein (CIP) box located between the FANCJ helicase motifs IV and V. Disruption of the FANCJ CIP box significantly reduces FANCJ association with the replisome, causing enhanced DNA damage, decreased replication fork recovery and fork asymmetry in stressful conditions. Cancer-relevant FANCJ CIP box variants display reduced AND-1-binding, a finding that suggests a potential role of the mutated FANCJ alleles in cancer predisposition.