title: Regulation of Prp43-mediated disassembly of spliceosomes by its cofactors Ntr1 and Ntr2.
abstract: The DEAH-box NTPase Prp43 disassembles spliceosomes in co-operation with the cofactors Ntr1/Spp382 and Ntr2, forming the NTR complex. How Prp43 is regulated by its cofactors to discard selectively only intron-lariat spliceosomes (ILS) and defective spliceosomes and to prevent disassembly of earlier and properly assembled/wild-type spliceosomes remains unclear. First, we show that Ntr1΄s G-patch motif (Ntr1GP) can be replaced by the GP motif of Pfa1/Sqs1, a Prp43΄s cofactor in ribosome biogenesis, demonstrating that the specific function of Ntr1GP is to activate Prp43 for spliceosome disassembly and not to guide Prp43 to its binding site in the spliceosome. Furthermore, we show that Ntr1΄s C-terminal domain (CTD) plays a safeguarding role by preventing Prp43 from disrupting wild-type spliceosomes other than the ILS. Ntr1 and Ntr2 can also discriminate between wild-type and defective spliceosomes. In both type of spliceosomes, Ntr1-CTD impedes Prp43-mediated disassembly while the Ntr1GP promotes disassembly. Intriguingly, Ntr2 plays a specific role in defective spliceosomes, likely by stabilizing Ntr1 and allowing Prp43 to enter a productive interaction with the GP motif of Ntr1. Our data indicate that Ntr1 and Ntr2 act as 'doorkeepers' and suggest that both cofactors inspect the RNP structure of spliceosomal complexes thereby targeting suboptimal spliceosomes for Prp43-mediated disassembly.
authors.affiliation: Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen, Germany.
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Fourmann
authors.affiliation: Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg August University of Göttingen, Justus-von-Liebig-Weg 11, Göttingen, Germany.
authors.forename: Marcel J
authors.initials: MJ
authors.lastname: Tauchert
authors.affiliation: Department of Molecular Structural Biology, Institute for Microbiology and Genetics, GZMB, Georg August University of Göttingen, Justus-von-Liebig-Weg 11, Göttingen, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Ficner
authors.affiliation: Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen, Germany.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Fabrizio
authors.affiliation: Department of Cellular Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, Göttingen, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Lührmann
mesh_terms: D020816:Amino Acid Motifs; D053487:DEAD-box RNA Helicases / Q000378:metabolism*; D000072417:Protein Domains; D012322:RNA Precursors / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D017381:Spliceosomes / Q000378:metabolism*
chemical_list: C507653:Ntr2 protein, S cerevisiae; C546353:PFA1 protein, S cerevisiae; D012322:RNA Precursors; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; C507652:Spp382 protein, S cerevisiae; C109034:PRP43 protein, S cerevisiae; D053487:DEAD-box RNA Helicases