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Observación en tiempo real del inicio de la transcripción de la ARN polimerasa II

Furqan M Fazal¹, Cong A Meng², Kenji Murakami³

¹Department of Applied Physics, Stanford University, Stanford, California 94305, USA.

|September 3, 2015

Resumen

La iniciación de la transcripción de la ARN polimerasa II implica un gran complejo de preiniciación (PIC, por sus siglas en inglés). Contrariamente a la creencia anterior, este complejo abre rápidamente una extensa burbuja de ADN para la transcripción, lo que permite el escape del promotor.

Área de la Ciencia:

Biología molecular
La bioquímica
La genética

Sus antecedentes:

La transcripción de la ARN polimerasa II es un proceso complejo.
La iniciación de la transcripción implica múltiples factores proteicos y interacciones con el ADN.
Los modelos anteriores proponían un desenrollamiento limitado del ADN durante la iniciación.

Objetivo del estudio:

Para investigar la dinámica en tiempo real del inicio de la transcripción.
Desafiar los modelos existentes de formación y escaneo de burbujas de transcripción.
Para aclarar el mecanismo de la fuga del promotor.

Principales métodos:

Ensamblaje de un complejo de preiniciación de 32 proteínas (PIC) de Saccharomyces cerevisiae.
Observación en tiempo real del inicio de la transcripción utilizando pinzas ópticas.
Análisis del desenrollamiento del ADN, síntesis de transcripción y escape del promotor.

Principales resultados:

El complejo de preiniciación abrió rápidamente una burbuja de transcripción extendida (promedio de 85 pares de bases).
La síntesis de transcripción se produjo hasta la longitud de la burbuja extendida.
La fuga fallida del promotor resultó en el colapso de la burbuja y el escaneo inútil.

Conclusiones:

El factor de transcripción IIH impulsa un rápido y extenso desenrollo del ADN durante la iniciación.
El proceso implica la síntesis de una transcripción más larga de lo que se pensaba anteriormente.
El escaneo fútil puede ocurrir debido a un escape fallido del promotor y al colapso de la burbuja.

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