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Señales para el desplazamiento del marco ribosómico en la región gag-pol del virus del sarcoma de Rous
T Jacks1, H D Madhani, F R Masiarz
1Department of Biochemistry and Biophysics, University of California, San Francisco 94143.
Cell
|November 4, 1988
Resumen
La síntesis de proteínas gag-pol del virus del sarcoma de Rous (RSV) se basa en el cambio de marco ribosomal. Este estudio identifica el sitio de cambio de marco y revela el deslizamiento del tRNA como el mecanismo clave, independiente del terminador de mordaza.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Virología Virología.
- Genética La genética.
Sus antecedentes:
- El virus del sarcoma de Rous (RSV) expresa las proteínas gag-pol esenciales a través del cambio de marco ribosomal.
- Este proceso implica un cambio en el marco de lectura traslacional para producir enzimas funcionales para la transcripción e integración inversa.
Objetivo del estudio:
- Para identificar el sitio preciso de desplazamiento de marco dentro del genoma del RSV.
- Para dilucidar el mecanismo molecular que impulsa el cambio de marco ribosómico en el RSV.
- Para investigar el papel de las estructuras de ARN y las mutaciones en la regulación de la síntesis de proteínas gag-pol.
Principales métodos:
- Localización del sitio del cambio de marco a través de la manipulación genética.
- Análisis del deslizamiento del tRNA y su papel en el cambio de marco.
- Mutagénesis dirigida al sitio de las secuencias pol y gag del RSV.
- Ensayos de síntesis in vitro para evaluar la producción de proteínas gag-pol.
- Análisis de la estructura del ARN, incluida la formación del bucle del tallo.
Principales resultados:
- El sitio de desplazamiento de marco fue localizado, y el mecanismo fue identificado como un deslizamiento de un solo nucleótido 5' de dos ARNt adyacentes.
- Se encontró que la secuencia del terminador de mordaza no era esencial para el desplazamiento de fotogramas.
- Las mutaciones en el RSV pol que afectan a la síntesis gag-pol se correlacionan con la capacidad de formar estructuras adyacentes de bucle de ARN tallo.
- Una secuencia mínima de ARN RSV de 147 nucleótidos que contiene el sitio de cambio de marco y el bucle del tallo fue suficiente para dirigir el cambio de marco.
Conclusiones:
- El cambio de marco ribosomal en el RSV está mediado principalmente por el deslizamiento del tRNA en un sitio específico.
- Las estructuras secundarias de ARN, particularmente los bucles del tallo cerca del sitio de cambio de marco, juegan un papel crucial en la regulación de este proceso.
- Una secuencia corta de ARN es suficiente para conferir la capacidad de cambio de marco, ofreciendo una herramienta para futuros estudios genéticos.
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