Release of the export adapter, Nmd3p, from the 60S ribosomal subunit requires Rpl10p and the cytoplasmic GTPase Lsg1p.
In eukaryotes, nuclear export of the large (60S) ribosomal subunit requires the adapter protein Nmd3p to provide the nuclear export signal. Here, we show that in yeast release of Nmd3p from 60S subunits in the cytoplasm requires the ribosomal protein Rpl10p and the G-protein, Lsg1p. Mutations in LSG1 or RPL10 blocked Nmd3-GFP shuttling into the nucleus and export of pre-60S subunits from the nucleus. Overexpression of NMD3 alleviated the export defect, indicating that the block in 60S export in lsg1 and rpl10 mutants results indirectly from failing to recycle Nmd3p. The defect in Nmd3p recycling and the block in 60S export in both lsg1 and rpl10 mutants was also suppressed by mutant Nmd3 proteins that showed reduced binding to 60S subunits in vitro. We propose that the correct loading of Rpl10p into 60S subunits is required for the release of Nmd3p from subunits by Lsg1p. These results suggest a coupling between recycling the 60S export adapter and activation of 60S subunits for translation.
Hedges
John
J
Section of Molecular Genetics and Microbiology, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712-1095, USA.
West
Matthew
M
Johnson
Arlen W
AW
D021581:Active Transport, Cell Nucleus; D001483:Base Sequence; D003593:Cytoplasm / Q000378:metabolism; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018628:Gene Dosage; D005800:Genes, Fungal; D008954:Models, Biological; D009154:Mutation; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013489:Suppression, Genetic; D013696:Temperature
D004271:DNA, Fungal; C117894:NMD3 protein, S cerevisiae; D016601:RNA-Binding Proteins; C093333:RPL10 protein, S cerevisiae; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; D019204:GTP-Binding Proteins; C475026:LSG1 protein, S cerevisiae