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In vivo Interrogation of Central Nervous System Translatome by Polyribosome Fractionation
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Arquitectura de un expresoma de transcripción y traducción
R Kohler1, R A Mooney2, D J Mills3
1Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany.
Science (New York, N.Y.)
|April 15, 2017
Resumen
Las bacterias vinculan la transcripción del ADN y la traducción del ARN mensajero (ARNm) a través de un complejo unificado de "expresoma". Este complejo, que involucra a la ARN polimerasa y los ribosomas, asegura una expresión génica eficiente y la función celular.
Área de la Ciencia:
- Biología molecular
- Microbiología
- Biología estructural
Sus antecedentes:
- La transcripción y la traducción están acopladas en las bacterias, pero el mecanismo subyacente sigue siendo poco conocido.
- Comprender este acoplamiento es crucial para comprender la regulación de la expresión génica en los procariotas.
Objetivo del estudio:
- Para aclarar la base estructural del acoplamiento transcripción-traducción en Escherichia coli.
- Identificar los componentes moleculares y las interacciones involucradas en la formación de un complejo transcriptor-traductor.
Principales métodos:
- Se utilizó la criomicroscopia electrónica (cryo-EM) para determinar la estructura del complejo de expresomas.
- Se realizaron ensayos bioquímicos in vitro y análisis de defectos de crecimiento in vivo para investigar el papel de los dominios proteicos específicos.
Principales resultados:
- Se caracterizó estructuralmente un complejo definido de "expresoma" formado por ARN polimerasa (RNAP) y el ribosoma.
- Se observó una protección continua de ~ 30 nucleótidos de ARNm desde el centro activo de RNAP hasta el centro de decodificación del ribosoma.
- El dominio carboxilo-terminal de la subunidad alfa de RNAP fue identificado como crítico para la interacción y el acoplamiento de RNAP-ribosoma.
Conclusiones:
- La estructura del expresoma proporciona una explicación mecanicista de cómo la traducción está acoplada a la transcripción.
- Este acoplamiento, facilitado por el expresoma, previene activamente las anomalías de transcripción como la pausa y la terminación.
- Los hallazgos revelan un aspecto fundamental de la regulación de la expresión génica bacteriana y la aptitud celular.
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