Nog2p, a putative GTPase associated with pre-60S subunits and required for late 60S maturation steps.
Eukaryotic ribosome maturation depends on a set of well ordered processing steps. Here we describe the functional characterization of yeast Nog2p (Ynr053cp), a highly conserved nuclear protein. Nog2p contains a putative GTP-binding site, which is essential in vivo. Kinetic and steady-state measurements of the levels of pre-rRNAs in Nog2p-depleted cells showed a defect in 5.8S and 25S maturation and a concomitant increase in the levels of both 27SB(S) and 7S(S) precursors. We found Nog2p physically associated with large pre-60S complexes highly enriched in the 27SB and 7S rRNA precursors. These complexes contained, besides a subset of ribosomal proteins, at least two additional factors, Nog1p, another putative GTP-binding protein, and Rlp24p (Ylr009wp), which belongs to the Rpl24e family of archaeal and eukaryotic ribosomal proteins. In the absence of Nog2p, the pre-60S ribosomal complexes left the nucleolus, but were retained in the nucleoplasm. These results suggest that transient, possibly GTP-dependent association of Nog2p with the pre-ribosomes might trigger late rRNA maturation steps in ribosomal large subunit biogenesis.
Saveanu
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Génétique des Interactions Macromoléculaires, Institut Pasteur (CNRS-URA2171), 25-28 rue du Dr Roux, 75724 Paris Cedex 15, France.
Bienvenu
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Namane
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Gleizes
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Gas
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Jacquier
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Fromont-Racine
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D021581:Active Transport, Cell Nucleus; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001665:Binding Sites; D015152:Blotting, Northern; D002466:Cell Nucleolus / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism; D005838:Genotype; D005947:Glucose / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006801:Humans; D017403:In Situ Hybridization; D007700:Kinetics; D008164:Luminescent Proteins / Q000378:metabolism; D013058:Mass Spectrometry; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D011132:Polyribosomes / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012335:RNA, Ribosomal / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013997:Time Factors
D018076:DNA, Complementary; D008164:Luminescent Proteins; D012333:RNA, Messenger; D012335:RNA, Ribosomal; D049452:Green Fluorescent Proteins; D012313:RNA; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D005947:Glucose