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El complejo de esquí de levadura: estructura cristalina y canalización de ARN al complejo de exosomas
Felix Halbach1, Peter Reichelt, Michaela Rode
1Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried/Munich, Germany.
Cell
|August 20, 2013
Resumen
El complejo Ski, crucial para el procesamiento del ARN, utiliza su estructura para unirse y procesar el ARN. Sus componentes, Ski2, Ski3 y Ski8, trabajan juntos para enhebrar el ARN al exosoma para su degradación.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Biología Estructural Biología estructural.
- La bioquímica es la bioquímica.
Sus antecedentes:
- El complejo Ski es esencial para las funciones del exosoma citoplasmático, incluida la rotación de ARN, la vigilancia y la interferencia.
- Es un conjunto multiproteico compuesto de subunidades Ski2, Ski3 y Ski8 en una estequiometría 1:1:2.
Objetivo del estudio:
- Para aclarar la base estructural de la función del complejo de esquí.
- Para entender cómo el complejo de esquí interactúa con el ARN y el exosoma.
- Investigar los mecanismos reguladores de las actividades del complejo de esquí.
Principales métodos:
- Determinación de la estructura cristalina del complejo de núcleos de esquí Saccharomyces cerevisiae (370 kDa).
- Pruebas bioquímicas para evaluar las actividades de unión al ARN, ATPasa y helicasa.
- Identificación de los motivos de las interacciones proteína-proteína.
Principales resultados:
- La estructura cristalina revela los motivos TPR de Ski3 que forman los brazos terminales N y C, posicionando el núcleo helicasa de Ski2 de forma central para una mayor unión al ARN.
- El brazo N-terminal Ski3 y el dominio de inserción Ski2 modulan alostéricamente las actividades de ATPasa y helicasa.
- Los datos bioquímicos sugieren un canal continuo de ARN para enhebrar el ARN al exosoma.
- Se identificó un motivo de unión Ski8 común a Ski3 y Spo11, lo que explica el papel de Ski8 en la descomposición y meiosis del ARNm.
Conclusiones:
- La estructura del complejo de esquí facilita el procesamiento y la degradación eficientes del ARN mediante el acoplamiento de las actividades de la helicasa y la exoribonucleasa.
- Las ideas estructurales explican la regulación alostérica de las funciones enzimáticas del complejo de esquí.
- El motivo de unión de Ski8 identificado proporciona una base molecular para el doble papel de Ski8 en el metabolismo del ARN y la recombinación meiotica.
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