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In vivo Application of the REMOTE-control System for the Manipulation of Endogenous Gene Expression
Published on: March 29, 2019
El lacrepresor actúa modificando el complejo de transcripción inicial para que no pueda salir del promotor
1Department of Microbiology, College of Physicians and Surgeons, Columbia University, New York, New York 10032.
Cell
|August 23, 1991
Resumen
La proteína lacrepresora impide que la ARN polimerasa alargue las transcripciones en el promotor lac UV5 aumentando un sitio de pausa natural. Este mecanismo bloquea el escape del promotor y genera moléculas de ARN cortas y abortivas.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Genética La genética.
- La bioquímica es la bioquímica.
Sus antecedentes:
- La proteína lacrepresora regula la expresión génica al unirse al operador lac.
- La ARN polimerasa inicia la transcripción en las regiones promotoras, pero el escape del promotor es un paso crítico.
- La transcripción abortiva ocurre cuando la ARN polimerasa libera fragmentos cortos de ARN sin alargar la transcripción.
Objetivo del estudio:
- Investigar el mecanismo por el cual el lacrepresor inhibe la actividad de la ARN polimerasa en el promotor lac UV5.
- Para determinar si la acción del represor implica aumentar los sitios de pausa del promotor intrínseco.
- Explorar las implicaciones de este mecanismo para el aclaramiento del promotor y la transcripción abortiva.
Principales métodos:
- Formación de un complejo conjunto entre la ARN polimerasa y el represor lac en el promotor lac UV5.
- Análisis de la síntesis de ARN, centrándose en la generación abortiva de oligómeros y la longitud de la transcripción.
- Investigando el efecto de la concentración de sustrato en la transcripción.
- Utilizando una mutación específica de la ARN polimerasa que imita el efecto del represor.
Principales resultados:
- El complejo conjunto entre la ARN polimerasa y el represor lac está bloqueado para que el promotor escape, produciendo oligómeros de ARN abortivos.
- La transcripción es muy sensible a la concentración de sustrato, lo que indica un sitio de pausa.
- El represor aumenta un sitio de pausa de alta concentración natural de nucleótidos (kNTP) dentro del promotor.
- Una mutación específica de la ARN polimerasa fenocopia el efecto del represor, bloqueando el aclaramiento del promotor y acortando los productos abortivos.
Conclusiones:
- El represor lac inhibe el alargamiento de la transcripción mediante la mejora de un sitio de pausa intrínseco al promotor, evitando así el escape del promotor.
- Este mecanismo de aumentar los sitios de pausa es probablemente una estrategia generalizada para regular la iniciación de la transcripción.
- Comprender estos mecanismos reguladores es crucial para comprender el control de la expresión génica.
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