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Distintos complejos ubiquitina-ligasa definen vías convergentes para la degradación de las proteínas ER
Pedro Carvalho1, Veit Goder, Tom A Rapoport
1Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
Cell
|July 29, 2006
Resumen
Los investigadores descubrieron distintas vías de degradación asociada al retículo endoplasmático (ERAD) en la levadura, cada una dirigida a proteínas mal plegadas en función de su ubicación. Estas vías convergen, ofreciendo un concepto unificado de ERAD potencialmente aplicable a las células humanas.
Área de la Ciencia:
- Biología celular Biología celular.
- La degradación de las proteínas.
- Mecanismos moleculares de las moléculas.
Sus antecedentes:
- Las proteínas mal plegadas del retículo endoplasmático (ER) se degradan a través de la degradación asociada al ER (ERAD).
- ERAD implica la poliubiquitilación y la degradación proteasómica citosólica de sustratos.
- Las distintas vías ERAD son cruciales para la homeostasis de las proteínas celulares.
Objetivo del estudio:
- Identificar y caracterizar los distintos complejos ubiquitina-ligasa que definen las diferentes vías de ERAD en Saccharomyces cerevisiae.
- Aclarar los mecanismos moleculares subyacentes al reconocimiento y la orientación de sustratos en ERAD.
- Proponer un concepto unificador para el ERAD aplicable a todas las especies.
Principales métodos:
- Identificación de distintos complejos ubiquitina-ligasa involucrados en el ERAD.
- Caracterización de las interacciones proteicas dentro de las vías ERAD (ERAD-L, ERAD-M, ERAD-C).
- Análisis de la orientación del sustrato basado en la ubicación del dominio de la proteína mal plegada (luminal, intramembrana, citosólico).
Principales resultados:
- Se identificaron distintas vías de ERAD (ERAD-L, ERAD-M, ERAD-C), cada una de las cuales utiliza ligasas de ubiquitina específicas (Hrd1p/Hrd3p, Doa10p).
- ERAD-L incluye Hrd1p/Hrd3p, Der1p y Usa1p para los dominios luminales mal plegados.
- ERAD-M es independiente de Usa1p y Der1p para los dominios intramembranales, mientras que ERAD-C se dirige a los dominios citosólicos a través de Doa10p.
- Todas las vías convergen en el complejo Cdc48p ATPasa para el procesamiento del sustrato.
Conclusiones:
- Existen tres vías ERAD distintas (ERAD-L, ERAD-M, ERAD-C) en la levadura, diferenciadas por el reconocimiento del sustrato y por complejos específicos de ubiquitina ligasa.
- Se propone un modelo unificador para ERAD, destacando los mecanismos conservados que implican la orientación al sustrato y la convergencia en Cdc48p.
- Estos hallazgos proporcionan información sobre el control de la calidad de las proteínas y pueden extenderse a los mecanismos ERAD de los mamíferos.
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