Prp2-mediated protein rearrangements at the catalytic core of the spliceosome as revealed by dcFCCS

Schematic representations of the substantial remodeling the B^actΔPrp2 spliceosome undergoes during the Prp2/ATP-mediated catalytic activation. Cwc24, Cwc27, the RES protein Bud13, Prp2, and Spp2 are released, while the U2 SF3a/b proteins are destabilized by Prp2/ATP, such that the BS adenosine becomes available for a nucleophile attack at the 5′ SS phosphodiester bond. At the same time, high-affinity binding sites are created for Yju2 and Cwc25, which are required to promote the first step of splicing.