The cotranscriptional assembly of snoRNPs controls the biosynthesis of H/ACA snoRNAs in Saccharomyces cerevisiae.
The carboxy-terminal domain (CTD) of RNA polymerase II large subunit acts as a platform to assemble the RNA processing machinery in a controlled way throughout the transcription cycle. In yeast, recent findings revealed a physical connection between phospho-CTD, generated by the Ctk1p kinase, and protein factors having a function in small nucleolar RNA (snoRNA) biogenesis. The snoRNAs represent a large family of polymerase II noncoding transcripts that are associated with highly conserved polypeptides to form stable ribonucleoprotein particles (snoRNPs). In this work, we have studied the biogenesis of the snoRNPs belonging to the box H/ACA class. We report that the assembly factor Naf1p and the core components Cbf5p and Nhp2p are recruited on H/ACA snoRNA genes very early during transcription. We also show that the cotranscriptional recruitment of Naf1p and Cbf5p is Ctk1p dependent and that Ctk1p and Cbf5p are required for preventing the readthrough into the snoRNA downstream genes. All these data suggest that proper cotranscriptional snoRNP assembly controls 3'-end formation of snoRNAs and, consequently, the release of a functional particle.
Ballarino
Monica
M
Institute Pasteur Fondazione Cenci-Bolognetti, Department of Genetics and Molecular Biology, University La Sapienza, P.le A. Moro 5, 00185 Rome, Italy.
Morlando
Mariangela
M
Pagano
Francesca
F
Fatica
Alessandro
A
Bozzoni
Irene
I
D047369:Chromatin Immunoprecipitation; D016213:Cyclins / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D006836:Hydro-Lyases / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008958:Models, Molecular; D009687:Nuclear Proteins / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D020537:RNA, Small Nucleolar / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017411:Ribonucleoproteins, Small Nuclear / Q000378:metabolism; D020718:Ribonucleoproteins, Small Nucleolar / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D014158:Transcription, Genetic
C118305:CTDK-I protein complex, S cerevisiae; D016213:Cyclins; D005656:Fungal Proteins; D008869:Microtubule-Associated Proteins; D009687:Nuclear Proteins; D020537:RNA, Small Nucleolar; D017411:Ribonucleoproteins, Small Nuclear; D020718:Ribonucleoproteins, Small Nucleolar; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; D006836:Hydro-Lyases; C082278:CBF5 protein, S cerevisiae