BH3-triggered structural reorganization drives the activation of proapoptotic BAX.
BAX is a proapoptotic BCL-2 family member that lies dormant in the cytosol until converted into a killer protein in response to cellular stress. Having recently identified the elusive trigger site for direct BAX activation, we now delineate by NMR and biochemical methods the essential allosteric conformational changes that transform ligand-triggered BAX into a fully activated monomer capable of propagating its own activation. Upon BAX engagement by a triggering BH3 helix, the unstructured loop between α helices 1 and 2 is displaced, the carboxy-terminal helix 9 is mobilized for membrane translocation, and the exposed BAX BH3 domain propagates the death signal through an autoactivating interaction with the trigger site of inactive BAX monomers. Our structure-activity analysis of this seminal apoptotic process reveals pharmacologic opportunities to modulate cell death by interceding at key steps of the BAX activation pathway.
Department of Pediatric Oncology and Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA.
Evripidis
E
Gavathiotis
Denis E
DE
Reyna
Marguerite L
ML
Davis
Gregory H
GH
Bird
Loren D
LD
Walensky
D000595:Amino Acid Sequence; D017209:Apoptosis; D001665:Binding Sites; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008024:Ligands; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017433:Protein Structure, Secondary; D021381:Protein Transport; D013329:Structure-Activity Relationship; D051028:bcl-2-Associated X Protein / Q000737:chemistry* / Q000378:metabolism*
D008024:Ligands; D051028:bcl-2-Associated X Protein