| Structural highlights
Function
[BAX_HUMAN] Accelerates programmed cell death by binding to, and antagonizing the apoptosis repressor BCL2 or its adenovirus homolog E1B 19k protein. Under stress conditions, undergoes a conformation change that causes translocation to the mitochondrion membrane, leading to the release of cytochrome c that then triggers apoptosis. Promotes activation of CASP3, and thereby apoptosis.[1] [2] [3] [4] [5] [6]
Publication Abstract from PubMed
To elicit apoptosis, BAX metamorphoses from an inert cytosolic monomer into homo-oligomers that permeabilize the mitochondrial outer membrane (MOM). A long-standing puzzle is that BH3 domains apparently activate BAX by not only its canonical groove but also a proposed site involving helices alpha1 and alpha6. Our mutagenesis studies reveal that late steps like oligomerization require activation through the groove but probably not earlier steps like MOM association. Conversely, alpha1 or alpha6 obstruction and alanine mutagenesis scanning implicate these helices early in BAX activation. The alpha1 and alpha6 mutations lowered BH3 binding, altered the BAX conformation, and reduced its MOM translocation and integration; their exposure of the BAX alpha1-alpha2 loop allosterically sequestered its alpha9 membrane anchor in the groove. The crystal structure of an alpha6 mutant revealed additional allosteric effects. The results suggest that the alpha1 and alpha6 region drives MOM association and integration, whereas groove binding favors subsequent steps toward oligomerization.
BAX Activation: Mutations Near Its Proposed Non-canonical BH3 Binding Site Reveal Allosteric Changes Controlling Mitochondrial Association.,Dengler MA, Robin AY, Gibson L, Li MX, Sandow JJ, Iyer S, Webb AI, Westphal D, Dewson G, Adams JM Cell Rep. 2019 Apr 9;27(2):359-373.e6. doi: 10.1016/j.celrep.2019.03.040. PMID:30970242[7]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Oltvai ZN, Milliman CL, Korsmeyer SJ. Bcl-2 heterodimerizes in vivo with a conserved homolog, Bax, that accelerates programmed cell death. Cell. 1993 Aug 27;74(4):609-19. PMID:8358790
- ↑ Schmitt E, Paquet C, Beauchemin M, Dever-Bertrand J, Bertrand R. Characterization of Bax-sigma, a cell death-inducing isoform of Bax. Biochem Biophys Res Commun. 2000 Apr 21;270(3):868-79. PMID:10772918 doi:http://dx.doi.org/10.1006/bbrc.2000.2537
- ↑ Chittenden T, Flemington C, Houghton AB, Ebb RG, Gallo GJ, Elangovan B, Chinnadurai G, Lutz RJ. A conserved domain in Bak, distinct from BH1 and BH2, mediates cell death and protein binding functions. EMBO J. 1995 Nov 15;14(22):5589-96. PMID:8521816
- ↑ Zhang H, Kim JK, Edwards CA, Xu Z, Taichman R, Wang CY. Clusterin inhibits apoptosis by interacting with activated Bax. Nat Cell Biol. 2005 Sep;7(9):909-15. Epub 2005 Aug 21. PMID:16113678 doi:http://dx.doi.org/10.1038/ncb1291
- ↑ Gavathiotis E, Suzuki M, Davis ML, Pitter K, Bird GH, Katz SG, Tu HC, Kim H, Cheng EH, Tjandra N, Walensky LD. BAX activation is initiated at a novel interaction site. Nature. 2008 Oct 23;455(7216):1076-81. PMID:18948948 doi:10.1038/nature07396
- ↑ Czabotar PE, Lee EF, Thompson GV, Wardak AZ, Fairlie WD, Colman PM. Mutation to Bax beyond the BH3 domain disrupts interactions with pro-survival proteins and promotes apoptosis. J Biol Chem. 2011 Mar 4;286(9):7123-31. Epub 2011 Jan 3. PMID:21199865 doi:10.1074/jbc.M110.161281
- ↑ Dengler MA, Robin AY, Gibson L, Li MX, Sandow JJ, Iyer S, Webb AI, Westphal D, Dewson G, Adams JM. BAX Activation: Mutations Near Its Proposed Non-canonical BH3 Binding Site Reveal Allosteric Changes Controlling Mitochondrial Association. Cell Rep. 2019 Apr 9;27(2):359-373.e6. doi: 10.1016/j.celrep.2019.03.040. PMID:30970242 doi:http://dx.doi.org/10.1016/j.celrep.2019.03.040
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