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Activation of Apoptosis by Cytoplasmic Microinjection of Cytochrome c
Published on: June 29, 2011
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Las estructuras cristalinas de Bax revelan cómo los dominios BH3 activan Bax y nuclean su oligomerización para
Peter E Czabotar1, Dana Westphal, Grant Dewson
1The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3052, Australia. czabotar@wehi.edu.au
Cell
|February 5, 2013
Resumen
La apoptosis celular incluye la oligomerización Bax o Bak. Este estudio revela cómo las proteínas BH3-only desencadenan la activación de Bax disociando sus dominios, facilitando la permeabilización de la membrana externa mitocondrial y la muerte celular.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- Biología celular Biología celular.
Sus antecedentes:
- La apoptosis, o muerte celular programada, es crucial para el desarrollo y la homeostasis tisular.
- La vía mitocondrial de la apoptosis está regulada por las proteínas de la familia Bcl-2, incluidos los pro-apoptóticos Bax y Bak, y sus activadores.
Objetivo del estudio:
- Para dilucidar los mecanismos estructurales por los cuales las proteínas BH3-sólo activan Bax.
- Comprender los cambios conformacionales que conducen a la oligomerización de Bax y la permeabilización de la membrana externa mitocondrial.
Principales métodos:
- Se utilizó la cristalografía de rayos X para determinar las estructuras de BaxΔC21 en complejo con péptidos BH3.
- Se realizó un análisis estructural de las hélices de Bax α2-α5 para investigar la homodimerización.
Principales resultados:
- Los péptidos BH3 se unen a la ranura canónica de Bax, induciendo la disociación del dominio.
- Se identificó una firma de secuencia conservada para los dominios BH3 del activador.
- Las hélices de Bax α2-α5 forman un homodímero simétrico, lo que sugiere un mecanismo de nucleación para la oligomerización.
- Una superficie lipofílica en el homodímero puede mediar la interacción de la membrana.
Conclusiones:
- Las proteínas BH3-only activan a Bax promoviendo la disociación de su dominio y la liberación de su propio dominio BH3.
- La homodimerización de Bax a través del compromiso mutuo del dominio BH3 es un paso clave para iniciar la oligomerización de Bax.
- Estos hallazgos proporcionan información crítica sobre las transiciones estructurales de Bax durante la inducción de la apoptosis.
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