Article
- The EMBO Journal (2001) 20, 6475 - 6484
- doi:10.1093/emboj/20.22.6475
Nog2p, a putative GTPase associated with pre-60S subunits and required for late 60S maturation steps
Cosmin Saveanu1, David Bienvenu1, Abdelkader Namane2, Pierre-Emmanuel Gleizes3, Nicole Gas3, Alain Jacquier1 and Micheline Fromont-Racine1
- Génétique des Interactions Macromoléculaires, Institut Pasteur (CNRS-URA2171) 25–28 rue du Dr Roux, 75724 Paris Cedex 15
- PT 'Proteomique', Institut Pasteur (CNRS-URA2185), 25–28 rue du Dr Roux, 75724 Paris Cedex 15
- Laboratoire de Biologie Moléculaire Eucaryote (LBME-CNRS), 118 route de Narbonne, 31062 Toulouse Cedex, France
Correspondence to:
Micheline Fromont-Racine, E-mail: mfromont@pasteur.fr
Received 15 June 2001; Accepted 27 September 2001; Revised 24 September 2001
Abstract
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 27SBS and 7SS 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.
Keywords:
- GTPase,
- nucleolus,
- nucleus,
- pre-rRNAprocessing,
- ribosome
