DEAD-box proteins: the driving forces behind RNA metabolism

Abstract

RNA helicases of the DEAD-box protein family all have nine characteristic motifs. These motifs clearly distinguish this family from other, highly related, RNA helicase families such as the DEAH-box or the Ski2 families. The motifs are contained within a core domain that is flanked by less-conserved regions, which are likely to represent specificity elements for substrate targeting, interaction with other proteins or cellular localization. RNA helicases of the DEAD-box family are required for different cellular processes such as transcription, pre-mRNA processing, ribosome biogenesis, nuclear mRNA export, translation initiation, RNA turnover and organelle function. The structure of the core element, which contains all the conserved motifs that are required for helicase activity, is very similar to viral RNA helicases and to DNA helicases, which indicates that the fundamental activities of these enzymes are similar. ATP-binding and hydrolysis by the core element induce conformational changes that are responsible for the enzymatic activity of these proteins; that is, unwinding of duplex RNA or disrupting RNA–protein complexes. The enzymatic activity varies among different proteins and can be more or less processive, parameters that are probably influenced by interacting partners and the substrate.