RNA binding mode of DHX37 suggests a mechanism for ATP-driven 3′–5′ translocation. (A) Side-by-side comparison of the structures of the DHX37-RNA (left) and Prp43-RNA-ADP.BeF3 − (PDB entry 5LTA, right) complexes. The helicases were superimposed using their RecA1 domains and are shown in identical orientations. (B) Superposition of DHX37 (colored as in A) and Prp43 (colored gray). The ADP.BeF3 − transition state mimic is shown in stick format. (C) Side-by-side views of the RNA binding channels in the DHX37-RNA (left) and Prp43-RNA-ADP.BeF3 − (right) complexes. While DHX37 accommodates a 5-nt stack (U6–U10) in the ATP-free state, Prp43 accommodates a 4-nt stack (U4–U7) in the ADP.BeF3− bound state. Motif IVa is omitted from the figures to give unobstructed view of the bound RNA. (D) Superposition of the RNA binding channels in DHX37 (colored as in A) and Prp43 (gray).
