Histone acetyltransferase and protein kinase activities copurify with a putative Xenopus RNA polymerase I holoenzyme self-sufficient for promoter-dependent transcription.
Mol Cell Biol
; 19(1): 796-806, 1999 Jan.
Article
em En
| MEDLINE
| ID: mdl-9858602
ABSTRACT
Mounting evidence suggests that eukaryotic RNA polymerases preassociate with multiple transcription factors in the absence of DNA, forming RNA polymerase holoenzyme complexes. We have purified an apparent RNA polymerase I (Pol I) holoenzyme from Xenopus laevis cells by sequential chromatography on five columns DEAE-Sepharose, Biorex 70, Sephacryl S300, Mono Q, and DNA-cellulose. Single fractions from every column programmed accurate promoter-dependent transcription. Upon gel filtration chromatography, the Pol I holoenzyme elutes at a position overlapping the peak of Blue Dextran, suggesting a molecular mass in the range of approximately 2 MDa. Consistent with its large mass, Coomassie blue-stained sodium dodecyl sulfate-polyacrylamide gels reveal approximately 55 proteins in fractions purified to near homogeneity. Western blotting shows that TATA-binding protein precisely copurifies with holoenzyme activity, whereas the abundant Pol I transactivator upstream binding factor does not. Also copurifying with the holoenzyme are casein kinase II and a histone acetyltransferase activity with a substrate preference for histone H3. These results extend to Pol I the suggestion that signal transduction and chromatin-modifying activities are associated with eukaryotic RNA polymerases.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas Quinases
/
Acetiltransferases
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Transcrição Gênica
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RNA Polimerase I
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Regiões Promotoras Genéticas
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Holoenzimas
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Proteínas de Saccharomyces cerevisiae
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Proteínas Pol1 do Complexo de Iniciação de Transcrição
Limite:
Animals
Idioma:
En
Revista:
Mol Cell Biol
Ano de publicação:
1999
Tipo de documento:
Article
País de afiliação:
Estados Unidos