Open AccessReduction in Ribosomal Protein Synthesis Is Sufficient To Explain Major Effects on Ribosome Production after Short-Term TOR Inactivation in Saccharomyces cerevisiae
Author(s) -
Alarich Reiter,
Robert Steinbauer,
Anja Philippi,
Jochen Gerber,
Herbert Tschochner,
Philipp Milkereit,
Joachim Griesenbeck
Publication year - 2011
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.01227-10
Subject(s) - ribosome biogenesis , biology , cycloheximide , ribosomal rna , ribosome , protein biosynthesis , ribosomal protein , microbiology and biotechnology , translation (biology) , 5.8s ribosomal rna , biochemistry , rna , messenger rna , gene
Ribosome synthesis depends on nutrient availability, sensed by the target of rapamycin (TOR) signaling pathway in eukaryotes. TOR inactivation affects ribosome biogenesis at the level of rRNA gene transcription, expression of ribosomal proteins (r-proteins) and biogenesis factors, preribosome processing, and transport. Here, we demonstrate that upon TOR inactivation, levels of newly synthesized ribosomal subunits drop drastically before the integrity of the RNA polymerase I apparatus is severely impaired but in good correlation with a sharp decrease in r-protein production. Inhibition of translation by cycloheximide mimics the rRNA maturation defect observed immediately after TOR inactivation. Both cycloheximide addition and the depletion of individual r-proteins also reproduce TOR-dependent nucleolar entrapment of specific ribosomal precursor complexes. We suggest that shortage of newly synthesized r-proteins after short-term TOR inactivation is sufficient to explain most of the observed effects on ribosome production.