ATP-dependent rRNA helicase required for pre-ribosomal RNA processing. Involved in the maturation of the 35S-pre-rRNA and to its cleavage to mature 18S rRNA. ATP + H2O = ADP + H(+) + phosphate ATPase activity is stimulated upon the addition of RNA. Optimum pH is 7.0-9.0. Interacts with the SSU processome. The Q motif is unique to and characteristic of the DEAD box family of RNA helicases and controls ATP binding and hydrolysis. Leads to improper processing of 35S precursor rRNA. Belongs to the DEAD box helicase family. DDX47/RRP3 subfamily.