DEAD-box RNA helicase involved in the assembly of the 50S ribosomal subunit. Has an RNA-dependent ATPase activity, which is specific for 23S rRNA, and a 3' to 5' RNA helicase activity that uses the energy of ATP hydrolysis to destabilize and unwind short rRNA duplexes. ATP + H2O = ADP + H(+) + phosphate Induced at 10 degrees Celsius. Contains an N-terminal domain that binds non-specifically to RNA and a C-terminal domain that binds specifically and tightly to hairpin 92 of 23S rRNA. Wild-type growth rate at 10 and 30 degrees Celsius, no change upon exposure to H(2)O(2) or diamide. Belongs to the DEAD box helicase family. DbpA subfamily.