ATP-dependent RNA helicase involved in mRNA turnover, and more specifically in mRNA decapping. Is involved in G1/S DNA-damage checkpoint recovery, probably through the regulation of the translational status of a subset of mRNAs. May also have a role in translation and mRNA nuclear export (By similarity). Blocks autophagy in nutrient-rich conditions by, at least partly, binding and repressing the expression of a set of ATG genes, including ATG3, ATG7, ATG8, ATG19, ATG20 and ATG22 (PubMed:26098573). VAD1-mediated repression of autophagy is regulated by TOR-dependent phosphorylation of the decapping enzyme DCP2 (PubMed:26098573). Regulates multiple virulence-associated genes (PubMed:15765146). Repression of autophagy by VAD1 also regulates the pathogenesis (PubMed:26098573). ATP + H2O = ADP + H(+) + phosphate Is concentrated in several cytoplasmic foci called P bodies (or cytoplasmic processing bodies) which represent sites of mRNA decapping and 5' to 3' exonucleotidic decay. The Q motif is unique to and characteristic of the DEAD box family of RNA helicases and controls ATP binding and hydrolysis. Leads to an accumulation of autophagic bodies and increases autophagic flux accompanied by increased accumulation of ATG8 mRNA and protein in nutrient-replete conditions (PubMed:26098573). Belongs to the DEAD box helicase family. DDX6/DHH1 subfamily.