ATP-dependent DNA helicase involved in DNA damage repair by homologous recombination and in genome maintenance (PubMed:10880470, PubMed:15126389, PubMed:15634678, PubMed:16121259). Capable of unwinding D-loops (PubMed:19136626). Plays a role in limiting crossover recombinants during mitotic DNA double-strand break (DSB) repair (PubMed:19136626). Prevents crossovers between ectopic sequences by removing substrates for MUS81-MMS4 or RAD1-RAD10 cleavage (PubMed:24119400). Component of a FANCM-MHF complex which promotes gene conversion at blocked replication forks, probably by reversal of the stalled fork (Probable) (PubMed:22912599). Binds to flap-structured DNA but not to non-flap nicked DNA, and participates in Okazaki fragment processing by stimulating the endonuclease activities of FEN1 and DNA2 (PubMed:19181670). Involved in recombination donor preference during mating-type switching via interaction with FKH1 (PubMed:27257873). ATP + H2O = ADP + H(+) + phosphate Interacts with the MHF histone-fold complex composed of MHF1 and MHF2 to form the FANCM-MHF complex (By similarity). Interacts with FHK1 (PubMed:27257873). Phosphorylation at both Thr-776 and Thr-785 is required for the interaction with FKH1. Causes transiant accumulation of ectopic joint molecules (JMs) (PubMed:24119400). Leads to a defect in donor preference during mating-type switching (PubMed:27257873). Does not affect FKH1's overlapping role with FKH2 of regulation of the expression of the CLB2 cluster of genes during the G2/M phase of the mitotic cell cycle (PubMed:27257873). Belongs to the DEAD box helicase family. DEAH subfamily. FANCM sub-subfamily.