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Toeprinting Analysis of Translation Initiation Complex Formation on Mammalian mRNAs
Published on: May 10, 2018
Los factores de ensamblaje del ribosoma evitan la iniciación prematura de la traducción por los intermediarios de
Bethany S Strunk1, Cherisse R Loucks, Min Su
1Chemical Biology Doctoral Program, University of Michigan, Ann Arbor, MI 48109, USA.
Science (New York, N.Y.)
|August 13, 2011
Resumen
Los investigadores utilizaron la microscopía cryoelectrónica para visualizar un paso clave en el ensamblaje de los ribosomas. Identificaron siete factores de ensamblaje de acción tardía (FA) que impiden que las subunidades ribosómicas 40S inmaduras inicien la síntesis de proteínas.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Biología Estructural Biología estructural.
- Biología celular Biología celular.
Sus antecedentes:
- La biogénesis de los ribosomas eucariotas implica más de 200 factores de ensamblaje (FA) y pasos complejos y ordenados.
- El ensamblaje del ribosoma comienza en el nucleolo y concluye en el citoplasma con subunidades maduras.
- Comprender las funciones precisas de los AF es crucial para comprender el control traslacional y la función celular.
Objetivo del estudio:
- Para determinar la estructura de un citoplasmático tardío 40S ribosoma ensamblaje intermedio intermedio.
- Para mapear las posiciones de los factores de ensamblaje de unión tardía (AF) en este intermedio.
- Aclarar los mecanismos por los cuales estos AFs evitan el inicio prematuro de la traducción.
Principales métodos:
- Utilizado cryo-microscopía de electrones (cryo-EM) para lograr un análisis estructural de alta resolución.
- Generó reconstrucciones cryo-EM de complejos preribosómicos con agotamientos específicos de la FA.
- Definido los sitios vinculantes y las disposiciones espaciales de siete AFs clave.
Principales resultados:
- La estructura cryo-EM de un intermediario de ensamblaje 40S citoplasmático tardío se resolvió a una resolución de 18 angstroms.
- Las posiciones de los siete AF de unión tardía fueron mapeadas con precisión.
- Estas FA bloquean colectivamente los sitios esenciales para el inicio de la traducción, incluida la unión al factor, el canal de ARNm y la unión de subunidades.
Conclusiones:
- Los AF de unión tardía actúan como puntos de control cruciales, impidiendo que las subunidades 40S inmaduras entren en la vía de traducción.
- Los mecanismos inhibidores redundantes aseguran que solo los ribosomas completamente ensamblados y funcionales participen en la síntesis de proteínas.
- Esta visión estructural proporciona una base molecular para el control de calidad de la biogénesis ribosómica.
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