title: A cotranscriptional model for 3'-end processing of the Saccharomyces cerevisiae pre-ribosomal RNA precursor.
abstract: Cleavage of the Saccharomyces cerevisiae primary ribosomal RNA (rRNA) transcript in the 3' external transcribed spacer (ETS) by Rnt1p generates the 35S pre-rRNA, the earliest detectable species in the pre-rRNA processing pathway. In this study we show that Rnt1p is concentrated in a subnucleolar dot-shaped territory distinct from the nucleolar body. The 35S pre-rRNA is localized at the periphery of the Rnt1p dot, in a pattern that suggests a diffusion of the 35S pre-rRNA from the site of Rnt1p processing. When plasmid-borne versions of the rDNA are used to express rRNAs, the Rnt1p territory reorganizes around these plasmids, suggesting a close association between Rnt1p and the plasmid-borne rDNA units. Rnt1p was found associated with the endogenous rDNA by chromatin immunoprecipitation. Deletion of functionally important Rnt1p domains result in a loss of the dot-shaped territory, showing that this subnucleolar territory corresponds to a functional site of processing. These results show that a large fraction of Rnt1p is localized at the site of transcription of the rDNA, suggesting that the cleavage of the primary pre-rRNA transcript to generate the 35S pre-rRNA is a cotranscriptional event.
authors.affiliation: Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California Los Angeles, Box 951569, Los Angeles, CA 90095-1569, USA.
authors.forename: Anthony K
authors.initials: AK
authors.lastname: Henras
authors.forename: Edouard
authors.initials: E
authors.lastname: Bertrand
authors.forename: Guillaume
authors.initials: G
authors.lastname: Chanfreau
mesh_terms: D002466:Cell Nucleolus / Q000378:metabolism; D008954:Models, Biological; D019913:Nuclear Localization Signals; D017434:Protein Structure, Tertiary; D026721:RNA 3' End Processing; D012322:RNA Precursors / Q000235:genetics* / Q000378:metabolism*; D012331:RNA, Fungal / Q000235:genetics* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D043244:Ribonuclease III / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D014158:Transcription, Genetic
chemical_list: D019913:Nuclear Localization Signals; D012322:RNA Precursors; D012331:RNA, Fungal; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C468367:RNT1 protein, S cerevisiae; D043244:Ribonuclease III