title: Nop53p interacts with 5.8S rRNA co-transcriptionally, and regulates processing of pre-rRNA by the exosome.
abstract: In eukaryotes, pre-rRNA processing depends on a large number of nonribosomal trans-acting factors that form intriguingly organized complexes. One of the early stages of pre-rRNA processing includes formation of the two intermediate complexes pre-40S and pre-60S, which then form the mature ribosome subunits. Each of these complexes contains specific pre-rRNAs, ribosomal proteins and processing factors. The yeast nucleolar protein Nop53p has previously been identified in the pre-60S complex and shown to affect pre-rRNA processing by directly binding to 5.8S rRNA, and to interact with Nop17p and Nip7p, which are also involved in this process. Here we show that Nop53p binds 5.8S rRNA co-transcriptionally through its N-terminal region, and that this protein portion can also partially complement growth of the conditional mutant strain Deltanop53/GAL::NOP53. Nop53p interacts with Rrp6p and activates the exosome in vitro. These results indicate that Nop53p may recruit the exosome to 7S pre-rRNA for processing. Consistent with this observation and similar to the observed in exosome mutants, depletion of Nop53p leads to accumulation of polyadenylated pre-rRNAs.
authors.affiliation: Department of Biochemistry, Institute of Chemistry, University of São Paulo, Brazil.
authors.forename: Daniela C
authors.initials: DC
authors.lastname: Granato
authors.forename: Glaucia M
authors.initials: GM
authors.lastname: Machado-Santelli
authors.forename: Carla C
authors.initials: CC
authors.lastname: Oliveira
mesh_terms: D001665:Binding Sites; D002466:Cell Nucleolus / Q000737:chemistry; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D005095:Exoribonucleases / Q000378:metabolism; D063326:Exosome Multienzyme Ribonuclease Complex; D015966:Gene Expression Regulation, Fungal; D005816:Genetic Complementation Test; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D026723:Polyadenylation; D012322:RNA Precursors / Q000096:biosynthesis / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012340:RNA, Ribosomal, 5.8S / Q000096:biosynthesis / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D014158:Transcription, Genetic
chemical_list: C504135:Nop53 protein, S cerevisiae; D009687:Nuclear Proteins; D012322:RNA Precursors; D012340:RNA, Ribosomal, 5.8S; D029701:Saccharomyces cerevisiae Proteins; D004259:DNA-Directed DNA Polymerase; C487545:PAP2 protein, S cerevisiae; D005095:Exoribonucleases; D063326:Exosome Multienzyme Ribonuclease Complex; C112610:RRP6 protein, S cerevisiae