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Un modelo topológico para la transcripción basado en el análisis del ángulo de desenrollamiento de E. coli RNA

H B Gamper, J E Hearst

|May 1, 1982

Resumen

La ARN polimerasa de Escherichia coli desenrolla el ADN por 17 pares de bases, una constante durante la transcripción. Esto sugiere que las actividades enzimáticas, desenrollar y rebobinar, facilitan la travesía de la hélice del ADN y el desplazamiento de la transcripción de ARN.

Área de la Ciencia:

Biología Molecular Biología Molecular
La bioquímica es la bioquímica.
Genética La genética.

Sus antecedentes:

El desenrollamiento del ADN es un paso crítico en la iniciación y elongación de la transcripción.
El mecanismo preciso de la manipulación de la hélice del ADN por la ARN polimerasa sigue siendo objeto de investigación.

Objetivo del estudio:

Para cuantificar el desenrollamiento del ADN por la ARN polimerasa de Escherichia coli.
Para dilucidar el papel del desenrollamiento del ADN en la iniciación y elongación de la transcripción.
Proponer un modelo para el movimiento de la ARN polimerasa a lo largo del ADN.

Principales métodos:

Medición de los ángulos de desenrollo del ADN para complejos binarios, de iniciación y ternales.
Utilizando una secuencia promotora única en el ADN del virus simio 40.
Los ensayos de transcripción se realizan a 37 grados C.

Principales resultados:

Todos los complejos exhibieron un ángulo consistente de desenrollo del ADN de 17 ± 1 pares de bases (580 ° ± 30 °).
El desenrollamiento del ADN es estabilizado por enzimas y mantenido a lo largo de la transcripción.
No se observó heterogeneidad en el ángulo de desenrollo durante el alargamiento.

Conclusiones:

Proponer la existencia de actividades de "unwindase" y "rewindase" dentro de la ARN polimerasa para el recorrido del ADN.
Sugieren un modelo en el que la unwindase desenrolla el ADN y la rewindase desplaza el ARN y vuelve a sellar la hélice.
Hipótesis de la formación híbrida de ARN-ADN como un mecanismo para la pausa y terminación de la polimerasa.

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