Cks1, Cdk1, and the 19S Proteasome Collaborate To Regulate Gene Induction-Dependent Nucleosome Eviction in Yeast▿
| Autor: | Susana R. Chaves, Christopher Baskerville, Steven I. Reed, Veronica P. C. C. Yu |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Předmět: |
Transcriptional Activation
Proteasome Endopeptidase Complex Saccharomyces cerevisiae Proteins Protein subunit Saccharomyces cerevisiae Cell Cycle Proteins F-box protein Histone H4 Histones 03 medical and health sciences Open Reading Frames 0302 clinical medicine Gene Expression Regulation Fungal CDC2 Protein Kinase Nucleosome Molecular Biology Transcription factor 030304 developmental biology Adaptor Proteins Signal Transducing 0303 health sciences biology Cell Biology Articles biology.organism_classification Molecular biology Chromatin Cell biology Nucleosomes Proteasome biology.protein 030217 neurology & neurosurgery |
| Popis: | Cks1, Cdk1 (Cdc28), and the proteasome are required for efficient transcriptional induction of GAL1 and other genes in Saccharomyces cerevisiae. We show here that one function of these proteins is to reduce nucleosome density on chromatin in a gene induction-specific manner. The transcriptional requirement for Cks1 can be bypassed if nucleosome density is reduced by an alternative pathway, indicating that this is the primary function of Cks1 in the context of gene induction. We further show that Cks1, Cdk1, and the 19S subunit of the proteasome are recruited to chromatin by binding directly to the histone H4 amino-terminal tail. However, this activity of the proteasome does not require the protease activity associated with the 20S subunit. These data suggest a model where binding of a complex consisting of Cks1, Cdk1, and the 19S proteasome to histone H4 leads to removal of nucleosomes via a nonproteolytic activity of the proteasome. Proteasomes are large multiprotein assemblies that are thought to function primarily in the turnover of cellular proteins (29, 39). In most cases, proteins destined for proteasomal degradation are tagged with covalent multiubiquitin chains (11). These chains are then recognized by regulatory caps at either end of the barrel-shaped catalytic core of the proteasome. Once bound to the proteasomal cap, substrates are stripped of their multiubiquitin chains and then threaded into the internal chamber of the proteasome barrel where three distinct protease activities cleave polypeptide chains into small peptides. The regulatory cap of the proteasome contains a ring of ATPases that abut the catalytic core and function to unwind and translocate folded proteins and to open an aperture into the catalytic core (37). Recently, proteasomal function has been linked to transcription in a number of different contexts. In Saccharomyces cerevisiae, genetic studies have yielded two classes of mutations in the ATPase subunits of the proteasome regulatory cap. The first class was identified as suppressors of a defective transcription factor, Gal4, and defined two genes, SUG1 and SUG2, which are now known to be identical to proteasomal ATPase genes RPT6 and RPT1, respectively (5, 9 |
| Databáze: | OpenAIRE |
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