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 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. Belongs to the DEAD box helicase family. DDX47/RRP3 subfamily.