Cytoplasmic recycling of 60S preribosomal factors depends on the AAA protein Drg1.
Allelic forms of DRG1/AFG2 confer resistance to the drug diazaborine, an inhibitor of ribosome biogenesis in Saccharomyces cerevisiae. Our results show that the AAA-ATPase Drg1 is essential for 60S maturation and associates with 60S precursor particles in the cytoplasm. Functional inactivation of Drg1 leads to an increased cytoplasmic localization of shuttling pre-60S maturation factors like Rlp24, Arx1, and Tif6. Surprisingly, Nog1, a nuclear pre-60S factor, was also relocalized to the cytoplasm under these conditions, suggesting that it is a previously unsuspected shuttling preribosomal factor that is exported with the precursor particles and very rapidly reimported. Proteins that became cytoplasmic under drg1 mutant conditions were blocked on pre-60S particles at a step that precedes the association of Rei1, a later-acting preribosomal factor. A similar cytoplasmic accumulation of Nog1 and Rlp24 in pre-60S-bound form could be seen after overexpression of a dominant-negative Drg1 variant mutated in the D2 ATPase domain. We conclude that the ATPase activity of Drg1 is required for the release of shuttling proteins from the pre-60S particles shortly after their nuclear export. This early cytoplasmic release reaction defines a novel step in eukaryotic ribosome maturation.
Pertschy
Brigitte
B
Institut für Molekulare Biowissenschaften. Karl-Franzens Universität Graz, Universitätsplatz 2, A-8010, Graz, Austria.
Saveanu
Cosmin
C
Zisser
Gertrude
G
Lebreton
Alice
A
Tengg
Martin
M
Jacquier
Alain
A
Liebminger
Eva
E
Nobis
Berthold
B
Kappel
Lisa
L
van der Klei
Ida
I
Högenauer
Gregor
G
Fromont-Racine
Micheline
M
Bergler
Helmut
H
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport / Q000502:physiology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D007381:Intermediate Filament Proteins / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010448:Peptide Initiation Factors / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012269:Ribosomal Proteins; D054683:Ribosome Subunits, Large, Eukaryotic / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
D002352:Carrier Proteins; D007381:Intermediate Filament Proteins; C475027:NOG1 protein, S cerevisiae; D009687:Nuclear Proteins; D010448:Peptide Initiation Factors; D010750:Phosphoproteins; D011498:Protein Precursors; D011993:Recombinant Fusion Proteins; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; C491609:TIF6 protein, S cerevisiae; D000251:Adenosine Triphosphatases; D019204:GTP-Binding Proteins; C463962:AFG2 protein, S cerevisiae