Abstract
The DEAH-box ATPase Prp2 plays a key role in the activation of the spliceosome as it promotes the transition from the B(act) to the catalytically active B* spliceosome. Here, four crystal structures of Prp2 are reported: one of the nucleotide-free state and three different structures of the ADP-bound state. The overall conformation of the helicase core, formed by two RecA-like domains, does not differ significantly between the ADP-bound and the nucleotide-free states. However, intrinsic flexibility of Prp2 is observed, varying the position of the C-terminal domains with respect to the RecA domains. Additionally, in one of the structures a unique ADP conformation is found which has not been observed in any other DEAH-box, DEAD-box or NS3/NPH-II helicase.