Negative regulation of Gcn4 and Msn2 transcription factors by Srb10 cyclin-dependent kinase.
Genes Dev
; 15(9): 1078-92, 2001 May 01.
Article
en En
| MEDLINE
| ID: mdl-11331604
ABSTRACT
The budding yeast transcriptional activator Gcn4 is rapidly degraded in an SCF(Cdc4)-dependent manner in vivo. Upon fractionation of yeast extracts to identify factors that mediate Gcn4 ubiquitination, we found that Srb10 phosphorylates Gcn4 and thereby marks it for recognition by SCF(Cdc4) ubiquitin ligase. Srb10 is a physiological regulator of Gcn4 stability because both phosphorylation and turnover of Gcn4 are diminished in srb10 mutants. Gcn4 is almost completely stabilized in srb10Delta pho85Delta cells, or upon mutation of all Srb10 phosphorylation sites within Gcn4, suggesting that the Pho85 and Srb10 cyclin-dependent kinases (CDKs) conspire to limit the accumulation of Gcn4. The multistress response transcriptional regulator Msn2 is also a substrate for Srb10 and is hyperphosphorylated in an Srb10-dependent manner upon heat-stress-induced translocation into the nucleus. Whereas Msn2 is cytoplasmic in resting wild-type cells, its nuclear exclusion is partially compromised in srb10 mutant cells. Srb10 has been shown to repress a subset of genes in vivo, and has been proposed to inhibit transcription via phosphorylation of the C-terminal domain of RNA polymerase II. We propose that Srb10 also inhibits gene expression by promoting the rapid degradation or nuclear export of specific transcription factors. Simultaneous down-regulation of both transcriptional regulatory proteins and RNA polymerase may enhance the potency and specificity of transcriptional inhibition by Srb10.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas Quinasas
/
Factores de Transcripción
/
Proteínas Fúngicas
/
Quinasas Ciclina-Dependientes
/
Proteínas de Saccharomyces cerevisiae
/
Proteínas de Unión al ADN
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Genes Dev
Asunto de la revista:
BIOLOGIA MOLECULAR
Año:
2001
Tipo del documento:
Article
País de afiliación:
Estados Unidos