title: Proteasomal degradation of Sfp1 contributes to the repression of ribosome biogenesis during starvation and is mediated by the proteasome activator Blm10.
abstract: The regulation of ribosomal protein (RP) gene transcription is tightly linked to the nutrient status of the cell and is under the control of metabolic signaling pathways. In Saccharomyces cerevisiae several transcriptional activators mediate efficient RP gene transcription during logarithmic growth and dissociate from RP gene promoters upon nutrient limitation. Repression of RP gene transcription appears to be regulated predominantly by posttranslational modification and cellular localization of transcriptional activators. We report here that one of these factors, Sfp1, is degraded by the proteasome and that the proteasome activator Blm10 is required for regulated Sfp1 degradation. Loss of Blm10 results in the stabilization and increased nuclear abundance of Sfp1 during nutrient limitation, increased transcription of RP genes, increased levels of RPs, and decreased rapamycin-induced repression of RP genes. Thus we conclude that proteasomal degradation of Sfp1 is mediated by Blm10 and contributes to the repression of ribosome biogenesis under nutrient depletion.
authors.affiliation: Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
authors.forename: Antonio Diaz
authors.initials: AD
authors.lastname: Lopez
authors.forename: Krisztina
authors.initials: K
authors.lastname: Tar
authors.forename: Undine
authors.initials: U
authors.lastname: Krügel
authors.forename: Thomas
authors.initials: T
authors.lastname: Dange
authors.forename: Ignacio Guerrero
authors.initials: IG
authors.lastname: Ros
authors.forename: Marion
authors.initials: M
authors.lastname: Schmidt
mesh_terms: D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D025141:Drug Resistance, Fungal / Q000187:drug effects; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D010641:Phenotype; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D020123:Sirolimus / Q000494:pharmacology; D015534:Trans-Activators / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: C500597:Blm10 protein, S cerevisiae; D004268:DNA-Binding Proteins; D012269:Ribosomal Proteins; C117421:SFP1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D003513:Cycloheximide; D046988:Proteasome Endopeptidase Complex; D020123:Sirolimus