title: Nop6, a component of 90S pre-ribosomal particles, is required for 40S ribosomal subunit biogenesis in Saccharomyces cerevisiae.
abstract: In Saccharomyces cerevisiae, ribosome biogenesis requires, in addition to rRNA and ribosomal proteins, a myriad of small nucleolar RNAs (snoRNAs) and over two hundred protein trans-acting factors. There are protein trans-acting factors predicted to participate in ribosome biogenesis that have not been so far characterized. Here, we report the functional analysis of the Nucleolar protein 6 (Nop6) in ribosome biogenesis. Our results show that Nop6 is needed for optimal 40S ribosomal subunit biogenesis. Deletion of NOP6 leads to an appropriate 20% reduction in 18S rRNA levels and therefore in 40S ribosomal subunits. This is due to mild inhibition of pre-rRNA processing at cleavage site A 2. Tandem affinity purification followed by mass spectrometry and northern blot analyses indicate that Nop6 is a component of 90S pre-ribosomal particles. rDNA chromatin immunoprecipitation experiments and analysis of the intracellular localisation of Nop6-eGFP after in vivo shut down of pre-rRNA transcription strongly suggest that Nop6 binds to the pre-rRNA early during transcription. Genetic data suggest that Nop6 and the snoRNA snR57 both interact similarly with the protein trans-acting factor Nep1. It has been proposed that snR57 and Nep1 participate in a pre-rRNA conformational switch that allows the proper assembly of 40S ribosomal protein S19. Our results strongly suggest that the role Nop6 might have in this conformational switch is independent of snR57.
authors.affiliation: Departamento de Genética, Universidad de Sevilla, Sevilla, Spain.
authors.forename: Juan José
authors.initials: JJ
authors.lastname: García-Gómez
authors.forename: Reyes
authors.initials: R
authors.lastname: Babiano
authors.forename: Simon
authors.initials: S
authors.lastname: Lebaron
authors.forename: Carine
authors.initials: C
authors.lastname: Froment
authors.forename: Bernard
authors.initials: B
authors.lastname: Monsarrat
authors.forename: Yves
authors.initials: Y
authors.lastname: Henry
authors.forename: Jesús
authors.initials: J
authors.lastname: de la Cruz
mesh_terms: D002466:Cell Nucleolus / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D009154:Mutation; D010641:Phenotype; D011485:Protein Binding; D012323:RNA Processing, Post-Transcriptional; D020537:RNA, Small Nucleolar / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000378:metabolism; D054682:Ribosome Subunits, Small, Eukaryotic / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C444457:EMG1 protein, S cerevisiae; C526036:Nop6 protein, S cerevisiae; D020537:RNA, Small Nucleolar; D016601:RNA-Binding Proteins; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins