RNA Specificity and Autoregulation of DDX17, a Modulator of MicroRNA Biogenesis

DDX17, a DEAD-box ATPase, is a multifunctional helicase important for various RNA functions, including microRNA maturation. Key questions for DDX17 include how it recognizes target RNAs and influences their structures, as well as how its ATPase activity may be regulated. Through crystal structures and biochemical assays, we show the ability of the core catalytic domains of DDX17 to recognize specific sequences in target RNAs. The RNA sequence preference of the catalytic core is critical for DDX17 to directly bind and remodel a specific region of primary microRNAs 3′ to the mature sequence, and consequently enhance processing by Drosha. Furthermore, we identify an intramolecular interaction between the N-terminal tail and the DEAD domain of DDX17 to have an autoregulatory role in controlling the ATPase activity. Thus, we provide the molecular basis for how cognate RNA recognition and functional outcomes are linked for DDX17. [Display omitted] •Crystal structures of human DDX17 core domains in multiple states are determined•DDX17 core domains exhibit RNA sequence preference via the RMFQ motif•DDX17 can enhance processing of pri-miRs by remodeling the 3′ flanking region•N-terminal tail of DDX17 can regulate the ATPase activity Ngo et al. reveal crystal structures of DEAD-box 17 (DDX17) and show that the core catalytic domains recognize RNA sequence motifs in primary transcripts of microRNAs, to regulate processing by Drosha. DDX17 also has a unique N-terminal tail that can attenuate the ATPase activity.