Has ATP-dependent RNA helicase activity in vitro. Acts as a thermosensitive RNA chaperone required for normal processing of pre-rRNA intermediates. Required for normal cell division at high temperatures. Required for a primary metabolism adaptation to high temperatures to support thermotolerant growth by regulating gene expression. ATP + H2O = ADP + H(+) + phosphate Helicase activity is activated by temperature increase. Interacts with U3 small nucleolar RNA (U3 snoRNA) as part of the ribosomal small subunit (SSU) processome. Localization is not affected by temperature. The Q motif is unique to and characteristic of the DEAD box family of RNA helicases and controls ATP binding and hydrolysis. Plant shows a high temperature-dependent growth repression. Belongs to the DEAD box helicase family. DDX47/RRP3 subfamily.