title: Inhibition of Pro-apoptotic BAX by a noncanonical interaction mechanism.
abstract: BCL-2 is a negative regulator of apoptosis implicated in homeostatic and pathologic cell survival. The canonical anti-apoptotic mechanism involves entrapment of activated BAX by a groove on BCL-2, preventing BAX homo-oligomerization and mitochondrial membrane poration. The BCL-2 BH4 domain also confers anti-apoptotic functionality, but the mechanism is unknown. We find that a synthetic α-helical BH4 domain binds to BAX with nanomolar affinity and independently inhibits the conformational activation of BAX. Hydrogen-deuterium exchange mass spectrometry demonstrated that the N-terminal conformational changes in BAX induced by a triggering BIM BH3 helix were suppressed by the BCL-2 BH4 helix. Structural analyses localized the BH4 interaction site to a groove formed by residues of α1, α1-α2 loop, and α2-α3 and α5-α6 hairpins on the BAX surface. These data reveal a previously unappreciated binding site for targeted inhibition of BAX and suggest that the BCL-2 BH4 domain may participate in apoptosis blockade by a noncanonical interaction mechanism.
authors: Department of Pediatric Oncology and the Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
authors: Lauren A
authors: LA
authors: Barclay
authors: Department of Chemistry and Chemical Biology, Barnett Institute of Chemical and Biological Analysis, Northeastern University, Boston, MA 02115, USA.
authors: Thomas E
authors: TE
authors: Wales
authors: Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
authors: Thomas P
authors: TP
authors: Garner
authors: Department of Pediatric Oncology and the Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
authors: Franziska
authors: F
authors: Wachter
authors: Department of Pediatric Oncology and the Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
authors: Susan
authors: S
authors: Lee
authors: Department of Pediatric Oncology and the Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
authors: Rachel M
authors: RM
authors: Guerra
authors: Department of Pediatric Oncology and the Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
authors: Michelle L
authors: ML
authors: Stewart
authors: Department of Pediatric Oncology and the Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
authors: Craig R
authors: CR
authors: Braun
authors: Department of Pediatric Oncology and the Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
authors: Gregory H
authors: GH
authors: Bird
authors: Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
authors: Evripidis
authors: E
authors: Gavathiotis
authors: Department of Chemistry and Chemical Biology, Barnett Institute of Chemical and Biological Analysis, Northeastern University, Boston, MA 02115, USA.
authors: John R
authors: JR
authors: Engen
authors: Department of Pediatric Oncology and the Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA. Electronic address: loren_walensky@dfci.harvard.edu.
authors: Loren D
authors: LD
authors: Walensky
mesh_terms: D000595:Amino Acid Sequence; D017209:Apoptosis; D001665:Binding Sites / Q000235:genetics; D041961:Deuterium Exchange Measurement / Q000379:methods; D006367:HeLa Cells; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: C494826:BAX protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein