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Artificial RNA Polymerase II Elongation Complexes for Dissecting Co-transcriptional RNA Processing Events
Published on: May 13, 2019
Un octámero de histona puede evitar una polimerasa transcriptor sin salir de la plantilla
V M Studitsky1, D J Clark, G Felsenfeld
1Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases National Institutes of Health Bethesda, Maryland 20892.
Cell
|January 28, 1994
Resumen
Los núcleos nucleosómicos se mueven a lo largo del ADN durante la transcripción, dando vueltas a la polimerasa transcriptor sin disociarse. Este mecanismo de translocación asegura la regulación de la expresión génica.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- La epigenética es la epigenética.
- Regulación genética Reglamento genético.
Sus antecedentes:
- Los nucleosomas son unidades fundamentales del empaque del ADN en los eucariotas.
- Comprender la dinámica de los nucleosomas durante la transcripción es crucial para la regulación de los genes.
- Los modelos anteriores proponían varios mecanismos para el desplazamiento de los nucleosomas.
Objetivo del estudio:
- Investigar el mecanismo de desplazamiento y reformación del núcleo del nucleosoma durante la transcripción in vitro.
- Para aclarar el papel de la longitud de la plantilla de ADN y la concentración de nucleótidos en el movimiento del nucleosoma.
- Proporcionar evidencia para un modelo de translocación específico de la dinámica del nucleosoma.
Principales métodos:
- El ensamblaje de núcleos nucleosómicos en plantillas de ADN definidas (227 bp y 262 bp) que contienen el promotor de la ARN polimerasa SP6.
- Los ensayos de transcripción in vitro se realizan con diferentes concentraciones de trifosfatos de ribonucleótidos (rNTP).
- Análisis de la posición del núcleo del nucleosoma con respecto al promotor después de la transcripción.
Principales resultados:
- La transcripción indujo la translocación del núcleo del nucleosoma sobre 75-80 bp, bloqueando el promotor.
- La transferencia de nucleosomas ocurrió intramolecularmente a bajas concentraciones de rNTP.
- La posición del nucleosoma en las plantillas más largas dependía de su posición inicial.
- Los datos sugieren la transferencia de octámero sin disociación del ADN.
Conclusiones:
- La evidencia sólida apoya un mecanismo de translocación del ADN para el reposicionamiento del nucleosoma durante la transcripción.
- El octámero del nucleosoma "pasa" alrededor de la polimerasa transcriptor.
- Este mecanismo permite la transcripción mientras se mantiene la integridad del nucleosoma.
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