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Estructura del complejo de terminación ribosómica de Escherichia coli con factor de liberación 2
Bruno P Klaholz1, Tillmann Pape, Andrey V Zavialov
1Department of Biological Sciences, Imperial College of Science, Technology and Medicine, London SW7 2AY, UK.
Nature
|January 4, 2003
Resumen
Los factores de liberación de clase I (RF) como RF2 terminan la síntesis de proteínas mediante el reconocimiento de codones de parada en el ARN mensajero. Este estudio revela el RF2
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Biología Estructural Biología estructural.
- La bioquímica es la bioquímica.
Sus antecedentes:
- La terminación de la síntesis de proteínas se basa en los factores de liberación de clase I (RF) que reconocen los codones de parada.
- Las RF desencadenan la liberación de polipéptidos del tRNA a través de la hidrólisis del peptidilo-tRNA.
- El mecanismo preciso para detener el reconocimiento del codón y la hidrólisis por RF sigue siendo elusivo.
Objetivo del estudio:
- Para aclarar el mecanismo estructural de la terminación traslacional.
- Para visualizar la interacción entre RF2 y el ribosoma durante la terminación.
Principales métodos:
- Microscopía criolectrónica de una sola partícula (cryo-EM) del ribosoma de Escherichia coli.
- Integración de las estructuras conocidas de 70S y RF2 en el mapa de densidad cryo-EM.
Principales resultados:
- RF2 adopta una conformación distinta en el ribosoma en comparación con su estructura aislada.
- Los dominios RF2 clave interactúan con los sitios ribosómicos: el dominio helicoidal amino-terminal con el sitio de unión del factor, el bucle SPF cerca del ARNm y el dominio GGQ con el centro de la peptidil-transferasa (PTC).
- RF2 une el centro de decodificación ribosómica y el PTC, imitando funcionalmente un tRNA.
Conclusiones:
- La conformación ribosómica de RF2 es crucial para su función en la terminación traslacional.
- La estructura proporciona información sobre cómo RF2 reconoce los codones de parada y cataliza la hidrólisis.
- Es probable que se emplee un mecanismo similar en la terminación traslacional eucariota.
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