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Transient binding of an activator BH3 domain to the Bak BH3-binding groove initiates Bak oligomerization

The mechanism by which the proapoptotic Bcl-2 family members Bax and Bak release cytochrome c from mitochondria is incompletely understood. In this paper, we show that activator BH3-only proteins bind tightly but transiently to the Bak hydrophobic BH3-binding groove to induce Bak oligomerization, li...

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Detalles Bibliográficos
Autores principales: Dai, Haiming, Smith, Alyson, Meng, X. Wei, Schneider, Paula A., Pang, Yuan-Ping, Kaufmann, Scott H.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2011
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3135403/
https://www.ncbi.nlm.nih.gov/pubmed/21727192
http://dx.doi.org/10.1083/jcb.201102027
Descripción
Sumario:The mechanism by which the proapoptotic Bcl-2 family members Bax and Bak release cytochrome c from mitochondria is incompletely understood. In this paper, we show that activator BH3-only proteins bind tightly but transiently to the Bak hydrophobic BH3-binding groove to induce Bak oligomerization, liposome permeabilization, mitochondrial cytochrome c release, and cell death. Analysis by surface plasmon resonance indicated that the initial binding of BH3-only proteins to Bak occurred with similar kinetics with or without detergent or mitochondrial lipids, but these reagents increase the strength of the Bak–BH3-only protein interaction. Point mutations in Bak and reciprocal mutations in the BH3-only proteins not only confirmed the identity of the interacting residues at the Bak–BH3-only protein interface but also demonstrated specificity of complex formation in vitro and in a cellular context. These observations indicate that transient protein–protein interactions involving the Bak BH3-binding groove initiate Bak oligomerization and activation.