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La autobiquitinación de la ligasa Hrd1 desencadena la retrotranslocación de la proteína en ERAD
Ryan D Baldridge1, Tom A Rapoport1
1Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
Cell
|June 21, 2016
Resumen
Los investigadores exploraron cómo las proteínas ER mal plegadas se mueven al citosol para la degradación. Encontraron que la ubiquitina ligasa Hrd1 probablemente forma un canal, guiando a las proteínas a través de las membranas durante la degradación asociada a ER (ERAD).
Área de la Ciencia:
- Biología celular
- Biología molecular
- La bioquímica
Sus antecedentes:
- Las proteínas mal plegadas se acumulan en el retículo endoplasmático (RE).
- La degradación asociada a ER (ERAD) elimina estas proteínas a través de la retrotranslocación al citosol y la degradación proteasómica.
- El mecanismo de retrotranslocación a través de la membrana ER sigue siendo incompletamente entendido.
Objetivo del estudio:
- Investigar el mecanismo de retrotranslocación mediada por ERAD de las proteínas luminales mal plegadas.
- Determinar el papel de la ubiquitina ligasa Hrd1 en este proceso.
- Para aclarar la función de la ATPasa Cdc48 en la extracción del sustrato.
Principales métodos:
- Reconstitución de la retrotranslocación utilizando proteínas purificadas de Saccharomyces cerevisiae.
- Se utilizan proteoliposomas que contienen la ubiquitina ligasa Hrd1.
- Se investigó la ubiquitinación del sustrato y el papel del dominio RING-finger de Hrd1.
Principales resultados:
- La retrotranslocación de un dominio luminal mal plegado se desencadena por la autobiquitinación de Hrd1.
- La ubiquitinación del sustrato se produce después de la autobiquitinación de Hrd1.
- La ATPasa Cdc48 no es necesaria para el paso de retrotranslocación en sí.
- La ubiquitinación de las lisinas Hrd1 es esencial para la ERAD in vitro e in vivo.
Conclusiones:
- Hrd1 juega un papel crucial en el inicio de la retrotranslocación.
- Es probable que Hrd1 forme un canal conductor de proteínas ubiquitinado.
- Este mecanismo facilita la eliminación de las proteínas mal plegadas del lumen ER.
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