title: Spliceosome activation by PRP2 ATPase prior to the first transesterification reaction of pre-mRNA splicing.
abstract: In addition to small nuclear RNAs and spliceosomal proteins, ATP hydrolysis is needed for nuclear pre-mRNA splicing. A number of RNA-dependent ATPases which are involved in several distinct ATP-dependent steps in splicing have been identified in Saccharomyces cerevisiae and mammals. These so-called DEAD/H ATPases contain conserved RNA helicase motifs, although RNA unwinding activity has not been demonstrated in purified proteins. Here we report the role of one such DEAH protein, PRP2 of S. cerevisiae, in spliceosome activation. PRP2 bound to a precatalytic spliceosome prior to the first step of splicing. By blocking the activity of a novel splicing factor(s), HP, which was involved in a post-PRP2 step, we found that PRP2 hydrolyzed ATP to cause a change in the spliceosome without the occurrence of splicing. The change was quite dramatic and could account for the previously reported differences between the precatalytic, pre-mRNA-containing spliceosome and the "active," intermediate-containing spliceosome. The post-PRP2-ATP spliceosome was further isolated and could carry out the subsequent reaction apparently in the absence of PRP2 and ATP. We hypothesize that PRP2 functions as a molecular motor, similar to some DExH ATPases in transcription, in the activation of the precatalytic spliceosome for the transesterification reaction.
authors.affiliation: Department of Molecular Biology, Beckman Research Institute of the City of Hope, Duarte, California 91010-3000, USA.
authors.forename: S H
authors.initials: SH
authors.lastname: Kim
authors.forename: R J
authors.initials: RJ
authors.lastname: Lin
mesh_terms: D000818:Animals; D053487:DEAD-box RNA Helicases; D005656:Fungal Proteins / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D008322:Mammals; D012322:RNA Precursors / Q000235:genetics*; D012326:RNA Splicing; D012331:RNA, Fungal / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D005656:Fungal Proteins; D012322:RNA Precursors; D012331:RNA, Fungal; D029701:Saccharomyces cerevisiae Proteins; C066490:PRP2 protein, S cerevisiae; D053487:DEAD-box RNA Helicases