title: U3 snoRNP and Rrp5p associate independently with Saccharomyces cerevisiae 35S pre-rRNA, but Rrp5p is essential for association of Rok1p.
abstract: Biogenesis of eukaryotic ribosomal subunits proceeds via a series of precursor ribonucleoprotein particles that correspond to different stages in the maturation pathway. The different pre-ribosomal particles each contain a distinct complement of non-ribosomal, trans-acting factors that are crucial for correct and efficient progress of the maturation process. Although in recent years we have gained considerable insight into the composition of the pre-ribosomal particles, our knowledge how the ordered association with and their dissociation from the pre-ribosome of these trans-acting factors is controlled is still quite limited. Here, we have studied the mutual dependence between three of these factors, Rrp5p, U3 snoRNP and Rok1p, all essential for the early stages of pre-rRNA processing/assembly, for association with the 35S pre-rRNA in Saccharomyces cerevisiae. Using co-immunoprecipitation assays, we show that Rrp5p and U3 snoRNP associate independently of each other and that the two factors do not detectably interact prior to incorporation into the pre-ribosome. In contrast, association of the putative RNA helicase Rok1p, which is known to genetically interact with Rrp5p, is absolutely dependent on the presence of the latter protein but does not require U3.
authors.affiliation: Section of Biochemistry and Molecular Biology, Faculty of Exact Sciences, BioCentrum Amsterdam, Vrije Universiteit, de Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
authors.forename: Harmjan R
authors.initials: HR
authors.lastname: Vos
authors.forename: Ralph
authors.initials: R
authors.lastname: Bax
authors.forename: Alex W
authors.initials: AW
authors.lastname: Faber
authors.forename: Jan C
authors.initials: JC
authors.lastname: Vos
authors.forename: Hendrik A
authors.initials: HA
authors.lastname: Raué
mesh_terms: D053487:DEAD-box RNA Helicases; D009687:Nuclear Proteins / Q000378:metabolism / Q000502:physiology; D020365:RNA Helicases / Q000378:metabolism; D012322:RNA Precursors / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism*; D016601:RNA-Binding Proteins; D020718:Ribonucleoproteins, Small Nucleolar / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism* / Q000502:physiology
chemical_list: D009687:Nuclear Proteins; D012322:RNA Precursors; D012335:RNA, Ribosomal; D016601:RNA-Binding Proteins; C102025:RRP5 protein, S cerevisiae; D020718:Ribonucleoproteins, Small Nucleolar; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; C117377:ribonucleoprotein, U3 small nucleolar; C120858:ROK1 protein, S cerevisiae; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases