Multifunctional enzyme that has both magnesium and ATP-dependent DNA-helicase activity and 3'->5' exonuclease activity towards double-stranded DNA with a 5'-overhang. Has no nuclease activity towards single-stranded DNA or blunt-ended double-stranded DNA. Binds preferentially to DNA substrates containing alternate secondary structures, such as replication forks and Holliday junctions. May play an important role in the dissociation of joint DNA molecules that can arise as products of homologous recombination, at stalled replication forks or during DNA repair. Alleviates stalling of DNA polymerases at the site of DNA lesions. Important for genomic integrity. Plays a role in the formation of DNA replication focal centers; stably associates with foci elements generating binding sites for RP-A (By similarity). Plays a role in double-strand break repair after gamma-irradiation. ATP + H2O = ADP + H(+) + phosphate Binds 2 magnesium ions per subunit. Has high activity with manganese and zinc ions (in vitro). Monomer, and homooligomer (PubMed:11863428, PubMed:18596042, PubMed:20159463). May exist as homodimer, homotrimer, homotetramer and/or homohexamer (PubMed:11863428, PubMed:18596042, PubMed:20159463). Homotetramer, or homohexamer, when bound to DNA (PubMed:11863428, PubMed:18596042, PubMed:20159463). Interacts via its N-terminal domain with WRNIP1 (By similarity). Interacts with EXO1, PCNA and SUPV3L1 (PubMed:12704184, PubMed:17961633). Interacts with PML (isoform PML-4) (PubMed:21639834). Interacts (via KBM motif) with XRCC5 and XRCC6; promoting recruitment to DNA damage sites (PubMed:27063109). Interacts with RECQL5; this interaction stimulates WRN helicase activity on DNA fork duplexes (PubMed:23180761). Gamma-irradiation leads to its translocation from nucleoli to nucleoplasm and PML regulates the irradiation-induced WRN relocation (PubMed:21639834). Localizes to DNA damage sites (PubMed:27063109). The KBM 2 (Ku-binding motif 2) and XLM (XLF-like motif) mediate cooperative interaction with XRCC5/Ku80 and XRCC6/Ku70 and recruitment to DNA damage sites. Phosphorylated by PRKDC. The disease is caused by variants affecting the gene represented in this entry. The disease may be caused by variants affecting the gene represented in this entry. Belongs to the helicase family. RecQ subfamily. WRN mutation db (Warner disease)