DNA helicase that possesses intrinsic ATP-dependent nucleosome-remodeling activity and is both required for DNA repair and heterochromatin organization. Promotes DNA end resection of double-strand breaks (DSBs) following DNA damage: probably acts by weakening histone DNA interactions in nucleosomes flanking DSBs (By similarity). Probable chromatin remodeling factor. Probable helicase-like transcription factor involved in transcriptional gene silencing. Associates with SUVR2 and contributes to transcriptional gene silencing at RNA-directed DNA methylation (RdDM) target loci but also at RdDM-independent target loci. May be involved in nucleosome positioning to form ordered nucleosome arrays on chromatin (PubMed:25420628). Interacts with SUVR2 and itself. By UV-C illumination (PubMed:15053760). Accumulates in response to the mutagens rose Bengal (RB) and methyl methane sulfonate (MMS) (PubMed:15133154). Induction by the mutagens rose Bengal (RB) and methyl methane sulfonate (MMS) is enhanced in progeny of Chernobyl plants exposed to ionizing radiation thus leading to a higher resistance to DNA damages. Belongs to the SNF2/RAD54 helicase family.