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Transición conformal de la maquinaria Sec inferida de las estructuras bacterianas SecYE
Tomoya Tsukazaki1, Hiroyuki Mori, Shuya Fukai
1Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8501, Japan.
Nature
|October 17, 2008
Resumen
El translocon Sec translocon es el
Área de la Ciencia:
- Biología estructural Biología estructural.
- Biología molecular La biología molecular.
- La translocación de proteínas por translocación.
Sus antecedentes:
- Más del 30% de las proteínas están integradas en la membrana o secretadas.
- El translocon Sec (SecYEG/Sec61) facilita la localización de proteínas a través de las membranas.
- La ATPasa SecA impulsa la traslocación post-traducional bacteriana.
Objetivo del estudio:
- Para determinar la estructura de alta resolución de la translocación SecYE de un organismo que contiene SecA.
- Para aclarar el mecanismo de la interacción SecA-SecYE y su papel en la translocación de proteínas.
Principales métodos:
- Cristalografía de rayos X (resolución 3.2-A) con una resolución de
- Formación compleja con fragmento Fab anti-SecY.
- Simulaciones de dinámica molecular de las simulaciones.
- Mapeo de disulfuro en el mapa.
Principales resultados:
- Se observó un estado "pre-abierto" de la translocación SecYE.
- Los fragmentos SecA y Fab se unen a un sitio común en SecY.
- La unión de SecA parece inducir una transición conformacional en SecYE.
- Se identificó una nueva interfaz SecA-SecYE, lo que sugiere cambios conformacionales cooperativos.
Conclusiones:
- El translocon SecYE existe en un estado dinámico "pre-abierto".
- La unión de SecA a SecY es crucial para iniciar cambios conformacionales en el translocon.
- Los cambios conformacionales cooperativos entre SecA y SecYE son esenciales para la formación de complejos funcionales y la translocación de proteínas.
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