In vivo degradation of RNA polymerase II largest subunit triggered by alpha-amanitin
Autor: | Olivier Bensaude, Van Trung Nguyen, Marc Vigneron, Marie-Françoise Dubois, Claude Kedinger, Federico Giannoni, Sook-Jae Seo |
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Rok vydání: | 1996 |
Předmět: |
endocrine system
Amanitins animal structures Transcription Genetic Protein Conformation Protein subunit Molecular Sequence Data RNA polymerase II alpha-Amanitin Biology law.invention Mice chemistry.chemical_compound law Transcription (biology) polycyclic compounds Genetics medicine Animals Humans Drug Interactions Amino Acid Sequence Enzyme Inhibitors Cells Cultured Cell Nucleus Dactinomycin Dose-Response Relationship Drug Fibroblasts Molecular biology Intercalating Agents Recombinant Proteins In vitro Cell nucleus medicine.anatomical_structure chemistry Recombinant DNA biology.protein RNA Polymerase II Research Article medicine.drug |
Zdroj: | Nucleic Acids Research. 24:2924-2929 |
ISSN: | 1362-4962 |
Popis: | Alpha-Amanitin is a well-known specific inhibitor of RNA polymerase II (RNAPII) in vitro and in vivo. It is a cyclic octapeptide which binds with high affinity to the largest subunit of RNAPII, RPB1. We have found that in murine fibroblasts exposure to alpha-amanitin triggered degradation of the RPB1 subunit, while other RNAPII subunits, RPB5 and RPB8, remained almost unaffected. Transcriptional inhibition in alpha-amanitin-treated cells was slow and closely followed the disappearance of RPB1. The degradation rate of RPB1 was alpha-amanitin dose dependent and was not a consequence of transcriptional arrest. Alpha-Amanitin-promoted degradation of RPB1 was prevented in cells exposed to actinomycin D, another transcriptional inhibitor. Epitope-tagged recombinant human RPB1 subunits were expressed in mouse fibroblasts. In cells exposed to alpha-amanitin the wild-type recombinant subunit was degraded like the endogenous protein, but a mutated alpha-amanitin-resistant subunit remained unaffected. Hence, alpha-amanitin did not activate a proteolytic system, but instead its binding to mRPB1 likely represented a signal for degradation. Thus, in contrast to other inhibitors, such as actinomycin D or 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole, which reversibly act on transcription, inhibition by alpha-amanitin cannot be but an irreversible process because of the destruction of RNAPII. |
Databáze: | OpenAIRE |
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