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Organización espacial del complejo de alargamiento de la transcripción en Escherichia coli
E Nudler1, I Gusarov, E Avetissova
1Department of Biochemistry, New York University Medical Center, New York, NY 10016, USA. evgeny.nudler@med.nyu.edu
Science (New York, N.Y.)
|July 17, 1998
Resumen
La ARN polimerasa utiliza una sola unidad integrada para la unión del ADN y la salida del ARN, estabilizando el complejo de transcripción. Las horquillas de ARN pueden interrumpir esta unidad, causando la disociación.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- La bioquímica es la bioquímica.
- Genética La genética.
Sus antecedentes:
- La ARN polimerasa forma un complejo de alargamiento ternario durante la síntesis de ARN.
- Este complejo involucra sitios específicos de unión de ácido nucleico: el sitio de unión de ADN de doble cadena (DBS), el sitio de unión heterodúplex de ARN-ADN (HBS) y el sitio de unión de ARN (RBS).
Objetivo del estudio:
- Para mapear los contactos de ADN y ARN dentro de la enzima ARN polimerasa.
- Investigar la relación funcional entre el DBS, el HBS y el RBS.
Principales métodos:
- Se empleó el enlace cruzado fotoquímico para identificar regiones específicas de aminoácidos que interactúan con el ADN y el ARN.
- Análisis de estas interacciones para determinar la disposición espacial y la integración funcional de los sitios de unión.
Principales resultados:
- Identificaron regiones específicas de proteínas involucradas en la unión de ácido nucleico.
- Inesperadamente se descubrió que las mismas regiones proteicas participan tanto en la unión al ADN (DBS) como en la salida del ARN (RBS).
- Esto sugiere que la entrada de ADN y la salida de ARN ocurren en un sitio localizado de manera cercana dentro de la ARN polimerasa.
Conclusiones:
- Los tres sitios de unión (RBS-HBS-DBS) funcionan como una unidad única e integrada.
- Esta unidad integrada probablemente estabiliza el complejo de alargamiento ternario.
- La formación de horquillas de ARN puede conducir a la disociación del complejo ternario al interrumpir esta unidad.
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