Dbp7p, a putative ATP-dependent RNA helicase from Saccharomyces cerevisiae, is required for 60S ribosomal subunit assembly.
Putative ATP-dependent RNA helicases are ubiquitous, highly conserved proteins that are found in most organisms and they are implicated in all aspects of cellular RNA metabolism. Here we present the functional characterization of the Dbp7 protein, a putative ATP-dependent RNA helicase of the DEAD-box protein family from Saccharomyces cerevisiae. The complete deletion of the DBP7 ORF causes a severe slow-growth phenotype. In addition, the absence of Dbp7p results in a reduced amount of 60S ribosomal subunits and an accumulation of halfmer polysomes. Subsequent analysis of pre-rRNA processing indicates that this 60S ribosomal subunit deficit is due to a strong decrease in the production of 27S and 7S precursor rRNAs, which leads to reduced levels of the mature 25S and 5.8S rRNAs. Noticeably, the overall decrease of the 27S pre-rRNA species is neither associated with the accumulation of preceding precursors nor with the emergence of abnormal processing intermediates, suggesting that these 27S pre-rRNA species are degraded rapidly in the absence of Dbp7p. Finally, an HA epitope-tagged Dbp7 protein is localized in the nucleolus. We propose that Dbp7p is involved in the assembly of the pre-ribosomal particle during the biogenesis of the 60S ribosomal subunit.
Daugeron
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Département de Biochimie Médicale, Centre Médical Universitaire, Université de Genève, Geneva, Switzerland. marie-claire.daugeron@medecine.unige.ch
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D000595:Amino Acid Sequence; D002466:Cell Nucleolus / Q000737:chemistry; D003001:Cloning, Molecular; D053487:DEAD-box RNA Helicases; D008969:Molecular Sequence Data; D009154:Mutation; D016366:Open Reading Frames / Q000235:genetics; D020365:RNA Helicases; D012316:RNA Nucleotidyltransferases / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional / Q000235:genetics; D012335:RNA, Ribosomal / Q000096:biosynthesis; D012340:RNA, Ribosomal, 5.8S / Q000096:biosynthesis; D012270:Ribosomes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins
D012322:RNA Precursors; D012335:RNA, Ribosomal; D012340:RNA, Ribosomal, 5.8S; D029701:Saccharomyces cerevisiae Proteins; C065039:RNA, ribosomal, 25S; D012316:RNA Nucleotidyltransferases; C112078:DBP7 protein, S cerevisiae; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases