title: Rrp5p, a trans-acting factor in yeast ribosome biogenesis, is an RNA-binding protein with a pronounced preference for U-rich sequences.
abstract: Rrp5p is a trans-acting factor important for biogenesis of both the 40S and 60S subunit of the Saccharomyces cerevisiae ribosome. The protein contains 12 tandemly repeated S1 RNA binding motifs in its N-terminal region, suggesting the ability to interact directly with the pre-rRNA. In vitro binding studies, using immunopurified Rrp5p and in vitro transcribed, 32P-UTP-labeled RNA fragments, revealed that Rrp5p is a general RNA-binding protein with a strong preference for single-stranded sequences rich in uridines. Co-immunoprecipitation studies in yeast cells expressing ProtA-tagged Rrp5p showed that the protein is still associated with pre-ribosomal particles containing 27SA2 pre-rRNA but not with particles containing the 27SB precursor. Thus, Rrp5p appears to dissociate from the 66S pre-ribosome upon or immediately after further processing of 27SA2 pre-rRNA, suggesting the presence of (an) important binding site(s) within the 3'-terminal portion of ITS1. The location of these possible binding site(s) was further delimited using rrp2-1 mutant cells, which accumulate the 5'-extended 5.8S pre-rRNA species. The results indicate that association of Rrp5p with the pre-ribosome is abolished upon removal of a 30-nt region downstream from site A2, which contains two short, single-stranded U stretches. Sequence comparison shows that only the most 5' of these two U-rich stretches is conserved among yeast species whose ITS1 can functionally replace the S. cerevisiae spacer. The implications for the role of Rrp5p in yeast ribosome biogenesis are discussed.
authors.affiliation: Section of Biochemistry and Molecular Biology, FEW, Vrije Universiteit, de Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
authors.forename: Paulo
authors.initials: P
authors.lastname: de Boer
authors.forename: Harmjan R
authors.initials: HR
authors.lastname: Vos
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: D001665:Binding Sites; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D012335:RNA, Ribosomal / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014529:Uridine / Q000378:metabolism
chemical_list: D009687:Nuclear Proteins; D012322:RNA Precursors; D012335:RNA, Ribosomal; D016601:RNA-Binding Proteins; C102025:RRP5 protein, S cerevisiae; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D014529:Uridine