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Un modelo basado en la estructura para el ciclo completo de transcripción de la polimerasa de la influenza
Joanna M Wandzik1, Tomas Kouba1, Manikandan Karuppasamy1
1European Molecular Biology Laboratory, 71 Avenue des Martyrs, CS 90181, 38042 Grenoble Cedex 9, France.
Cell
|April 19, 2020
Resumen
La polimerasa de influenza se une de manera única a ambos extremos de su plantilla de ARN a lo largo de la transcripción. Este mecanismo asegura la producción eficiente de ARNm y la poliadenilación de los complejos de ribonucleoproteínas virales (vRNP).
Área de la Ciencia:
- Biología molecular
- Virología
- Biología estructural
Sus antecedentes:
- La polimerasa de la influenza sintetiza ARN mensajeros (ARNm) a partir de plantillas de ARN viral (ARNv) dentro de las partículas de ribonucleoproteína (ARNv).
- Comprender el mecanismo de la polimerasa es crucial para desarrollar estrategias antivirales.
Objetivo del estudio:
- Visualizar la dinámica conformacional de la polimerasa de la influenza durante todo el ciclo de transcripción.
- Para aclarar la trayectoria del ARN de la plantilla y su interacción con la polimerasa.
- Comprender los mecanismos moleculares del encapsulamiento, poliadenilación y terminación del ARNm.
Principales métodos:
- Se utilizó la microscopía cryoelectrónica (cryo-EM) para capturar instantáneas del complejo polimerasa.
- Análisis de los cambios conformacionales a lo largo del ciclo de transcripción, desde la preiniciación hasta la terminación.
Principales resultados:
- El extremo 3' de la plantilla de ARNv vuelve a unirse a un sitio específico de la polimerasa después de salir del sitio activo, permaneciendo unido durante toda la transcripción.
- Esta vinculación obliga a la plantilla a hacer un bucle, lo que permite la translocación y la síntesis continua.
- La poliadenilación se produce a través de la tartamudez en la uridina 17 debido a una conexión del extremo 5' de la plantilla tensada en la terminación.
Conclusiones:
- La polimerasa de la influenza se une firmemente y protege ambos extremos de la plantilla de ARNv durante la transcripción.
- Este proceso permite la producción eficiente de múltiples ARNm de un solo vRNP.
- Las dinámicas visualizadas proporcionan una comprensión completa de la síntesis de ARNm de la influenza.
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