title: Genetic evidence for 18S rRNA binding and an Rps19p assembly function of yeast nucleolar protein Nep1p.
abstract: The nucleolar protein Nep1 and its human homologue were previously shown to be involved in the maturation of 18S rRNA and to interfere directly or indirectly with a methylation reaction. Here, we report that the loss-of-function mutation Deltasnr57 and multicopy expression of the ribosomal 40S subunit protein 19 (Rps19p) can partially suppress the Saccharomyces cerevisiae Deltanep1 growth defect. SnR57 mediates 2'-O-ribose-methylation of G(1570) in the 18S rRNA. By performing a three-hybrid screen, we isolated several short RNA sequences with strong binding affinity to Nep1p. All isolated RNAs shared a six-nucleotide consensus motif C/UUCAAC. Furthermore, one of the isolated RNAs exactly corresponded to nucleotides 1553-1577 of the 18S rRNA, which includes G(1570), the site of snR57-dependent 18S rRNA methylation. From protein-protein crosslink data and the cryo-EM map of the S. cerevisiae small ribosomal subunit, we suggest that Rps19p is localized in close vicinity to the Nep1p 18S rRNA binding site. Our results suggest that Nep1p binds adjacent to helix 47 of the 18S rRNA and possibly supports the association of Rps19p to pre-ribosomal particles.
authors.affiliation: Institute of Molecular Biosciences, Johann Wolfgang Goethe-University, Marie-Curie-Str. 9, 60439 Frankfurt/Main, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Buchhaupt
authors.forename: Britta
authors.initials: B
authors.lastname: Meyer
authors.forename: Peter
authors.initials: P
authors.lastname: Kötter
authors.forename: Karl-Dieter
authors.initials: KD
authors.lastname: Entian
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002466:Cell Nucleolus / Q000378:metabolism*; D019175:DNA Methylation; D004251:DNA Transposable Elements / Q000235:genetics; D016681:Genome, Fungal / Q000235:genetics; D016254:Mutagenesis, Insertional; D009154:Mutation / Q000235:genetics; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D012337:RNA, Ribosomal, 18S / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020537:RNA, Small Nucleolar / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D013489:Suppression, Genetic; D020798:Two-Hybrid System Techniques
chemical_list: D004251:DNA Transposable Elements; C444457:EMG1 protein, S cerevisiae; D012337:RNA, Ribosomal, 18S; D020537:RNA, Small Nucleolar; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; C040343:ribosomal protein S19