A membrane-targeted BID BCL-2 homology 3 peptide is sufficient for high potency activation of BAX in vitro.
The multidomain pro-apoptotic proteins BAX and BAK constitute an essential gateway to mitochondrial dysfunction and programmed cell death. Among the "BCL-2 homology (BH) 3-only" members of pro-apoptotic proteins, truncated BID (tBID) has been implicated in direct BAX activation, although an explicit molecular mechanism remains elusive. We find that BID BH3 peptide alone at submicromolar concentrations cannot activate BAX or complement BID BH3 mutant-tBID in mitochondrial and liposomal release assays. Because tBID contains structurally defined membrane association domains, we investigated whether membrane targeting of BID BH3 peptide would be sufficient to restore its pro-apoptotic activity. We developed a Ni(2+)-nitrilotriacetic acid liposomal assay system that efficiently conjugates histidine-tagged peptides to a simulated outer mitochondrial membrane surface. Strikingly, nanomolar concentrations of a synthetic BID BH3 peptide that is chemically tethered to the liposomal membrane activated BAX almost as efficiently as tBID itself. These results highlight the importance of membrane targeting of the BID BH3 domain in tBID-mediated BAX activation and support a model in which tBID engages BAX to trigger its pro-apoptotic activity.
Oh
Kyoung Joon
KJ
Howard Hughes Medical Institute, the Department of Pathology and Medicine, Harvard Medical School, Dana-Farber Cancer Institute, Boston, MA 02115, USA. kyoung_joon_oh@dfci.harvard.edu
Barbuto
Scott
S
Pitter
Kenneth
K
Morash
Joel
J
Walensky
Loren D
LD
Korsmeyer
Stanley J
SJ
D017209:Apoptosis; D051023:BH3 Interacting Domain Death Agonist Protein / Q000737:chemistry / Q000502:physiology*; D006639:Histidine / Q000737:chemistry; D006801:Humans; D066298:In Vitro Techniques; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D011485:Protein Binding; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000737:chemistry / Q000502:physiology*; D011994:Recombinant Proteins / Q000737:chemistry; D051028:bcl-2-Associated X Protein / Q000502:physiology*; D051020:bcl-X Protein / Q000378:metabolism
D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D008055:Lipids; D008081:Liposomes; D010455:Peptides; D019253:Proto-Oncogene Proteins c-bcl-2; D011994:Recombinant Proteins; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; D006639:Histidine