DEAD-box RNA helicase that plays a role in 70S ribosome assembly. May work in conjunction with the cold shock proteins to ensure proper initiation of transcription at low and optimal temperatures. ATP + H2O = ADP + H(+) + phosphate Interacts with CspB when cells are transcriptionally active. May interact with RNA helicases CshA and DbpA (DeaD), may be a component of a possible RNA degradosome complex composed of rny, rnja, rnjb, pnp, pfkA and eno (although rnjA and rnjB's presence is unclear). Specifically interacts with pnp and rny (PubMed:20572937). Shows transcription-dependent localization at subcellular sites surrounding the nucleoid. Induced by cold shock (PubMed:12399512). In rich medium highest expression in logarithmic growth, expression decreases and then disappears in stationary phase (at protein level) (PubMed:20572937, PubMed:23175651). Protein level not increased at 16 degrees Celsius. Not detected in minimal medium (at protein level) (PubMed:20572937). No difference in growth at 37 or 15 degrees Celsius (PubMed:16352840), decreased growth at 16 degrees Celsius (PubMed:23175651). The presence of CshA or CshB is essential for viability; in a cshA disruption mutant further depletion of cshB stops growth after 1 cell duplication (PubMed:16352840). Others show a quadruple disruption of all RNA helicases (cshA, cshB, deaD, yfmL) was not lethal at 37 degrees Celsius, although both 50S and 70S ribosomes are decreased, but growth stops at 16 degrees (PubMed:23175651). A double cshB-cspB disruption mutant cannot be made. A double cshB-cspD mutant grows slowly at 15 degrees Celsius (PubMed:16352840). Decreased amounts of 70S ribosomes (PubMed:23175651). Belongs to the DEAD box helicase family.