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Fidelidad de la transcripción y corrección de pruebas por ARN polimerasa II
M J Thomas1, A A Platas, D K Hawley
1Institute of Molecular Biology, Department of Biology, University of Oregon, Eugene 97403, USA.
Cell
|May 30, 1998
Resumen
La ARN polimerasa humana II (pol II) posee capacidades intrínsecas de corrección de pruebas. Con la ayuda de la proteína SII, pol II elimina efectivamente los nucleótidos incorrectos durante la transcripción, asegurando la precisión del ARN.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- La bioquímica es la bioquímica.
- Genética La genética.
Sus antecedentes:
- La ARN polimerasa II (pol II) es crucial para la transcripción génica.
- La capacidad intrínseca de corrección de pruebas de pol II durante la transcripción no se entiende completamente.
- Se sabe que la proteína SII modula la actividad de la nucleasa.
Objetivo del estudio:
- Para investigar la actividad de la 3'-->5' nucleasa del pol II humano para su revisión durante la transcripción.
- Determinar el papel de la proteína SII en la mejora de la revisión de Pol II.
- Comprender el mecanismo de discriminación de nucleótidos por el pol II.
Principales métodos:
- Ensayos de transcripción in vitro utilizando la ARN polimerasa humana II. han sido realizados.
- Utilizando la proteína SII para estimular la actividad de la 3'-->5' nucleasa.
- Evaluación de la eliminación de nucleótidos mal incorporados de las transcripciones de ARN nacientes.
- Empleando la incorporación de monofosfato de inosina para sondear la cinética de adición de nucleótidos.
Principales resultados:
- El pol II humano demostró la eliminación cuantitativa de nucleótidos mal incorporados en presencia de SII.
- La discriminación entre bases correctas e incorrectas se basó en la tasa de adición subsecuente de nucleótidos.
- La incorporación de monofosfato de inosina (IMP) inhibió significativamente la siguiente adición de nucleótidos, similar a las bases no coincidentes.
- La adición de SII alteró la composición de la base de ARN, favoreciendo la incorporación de nucleótidos correcta (GMP) sobre la incorrecta (IMP).
Conclusiones:
- La ARN polimerasa humana II posee un mecanismo intrínseco de corrección de pruebas mediado por su actividad de 3'-->5' nucleasa.
- La proteína SII mejora significativamente esta capacidad de revisión durante la transcripción.
- La tasa de adición de nucleótidos es un factor clave en la capacidad de pol II para discriminar y eliminar bases incorrectas, asegurando la fidelidad del ARN.
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