The target of the DEAH-box NTP triphosphatase Prp43 in Saccharomyces cerevisiae spliceosomes is the U2 snRNP-intron interaction
Jean-Baptiste Fourmann,
Olexandr Dybkov,
Dmitry E Agafonov,
Marcel J Tauchert,
Henning Urlaub,
Ralf Ficner,
Patrizia Fabrizio,
Reinhard Lührmann
Affiliations
Jean-Baptiste Fourmann
Department of Cellular Biochemistry, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
Olexandr Dybkov
Department of Cellular Biochemistry, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
Dmitry E Agafonov
Department of Cellular Biochemistry, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
Marcel J Tauchert
Department of Molecular Structure Biology, Institute for Microbiology and Genetics, Georg August University of Göttingen, Göttingen, Germany
Henning Urlaub
Bionalytics, Institute for Clinical Chemistry, University Medical Center Göttingen, Göttingen, Germany; Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
Ralf Ficner
Department of Molecular Structure Biology, Institute for Microbiology and Genetics, Georg August University of Göttingen, Göttingen, Germany
Patrizia Fabrizio
Department of Cellular Biochemistry, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
The DEAH-box NTPase Prp43 and its cofactors Ntr1 and Ntr2 form the NTR complex and are required for disassembling intron-lariat spliceosomes (ILS) and defective earlier spliceosomes. However, the Prp43 binding site in the spliceosome and its target(s) are unknown. We show that Prp43 fused to Ntr1's G-patch motif (Prp43_Ntr1GP) is as efficient as the NTR in ILS disassembly, yielding identical dissociation products and recognizing its natural ILS target even in the absence of Ntr1’s C-terminal-domain (CTD) and Ntr2. Unlike the NTR, Prp43_Ntr1GP disassembles earlier spliceosomal complexes (A, B, Bact), indicating that Ntr2/Ntr1-CTD prevents NTR from disrupting properly assembled spliceosomes other than the ILS. The U2 snRNP-intron interaction is disrupted in all complexes by Prp43_Ntr1GP, and in the spliceosome contacts U2 proteins and the pre-mRNA, indicating that the U2 snRNP-intron interaction is Prp43’s major target.
