2xa0 | pdb_00002xa0
Crystal structure of BCL-2 in complex with a BAX BH3 peptide
Structural highlights
Disease[BCL2_HUMAN] Note=A chromosomal aberration involving BCL2 has been found in chronic lymphatic leukemia. Translocation t(14;18)(q32;q21) with immunoglobulin gene regions. BCL2 mutations found in non-Hodgkin lymphomas carrying the chromosomal translocation could be attributed to the Ig somatic hypermutation mechanism resulting in nucleotide transitions. Function[BCL2_HUMAN] Suppresses apoptosis in a variety of cell systems including factor-dependent lymphohematopoietic and neural cells. Regulates cell death by controlling the mitochondrial membrane permeability. Appears to function in a feedback loop system with caspases. Inhibits caspase activity either by preventing the release of cytochrome c from the mitochondria and/or by binding to the apoptosis-activating factor (APAF-1).[1] [BAX_MOUSE] 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. BAX deficiency leads to lymphoid hyperplasia and male sterility, because of the cessation of sperm production.[2] [3] Publication Abstract from PubMedInteractions between the BCL-2 family proteins determine the cell's fate to live or die. How they interact with each other to regulate apoptosis remains as an unsettled central issue. So far, the antiapoptotic BCL-2 proteins are thought to interact with BAX weakly, but the physiological significance of this interaction has been vague. Herein, we show that recombinant BCL-2 and BCL-w interact potently with a BCL-2 homology (BH) 3 domain-containing peptide derived from BAX, exhibiting the dissociation constants of 15 and 23 nM, respectively. To clarify the basis for this strong interaction, we determined the three-dimensional structure of a complex of BCL-2 with a BAX peptide spanning its BH3 domain. It revealed that their interactions extended beyond the canonical BH3 domain and involved three nonconserved charged residues of BAX. A novel BAX variant, containing the alanine substitution of these three residues, had greatly impaired affinity for BCL-2 and BCL-w, but was otherwise indistinguishable from wild-type BAX. Critically, the apoptotic activity of the BAX variant could not be restrained by BCL-2 and BCL-w, pointing that the observed tight interactions are critical for regulating BAX activation. We also comprehensively quantified the binding affinities between the three BCL-2 subfamily proteins. Collectively, the data show that due to the high affinity of BAX for BCL-2, BCL-w and A1, and of BAK for BCL-X(L), MCL-1 and A1, only a subset of BH3-only proteins, commonly including BIM, BID and PUMA, could be expected to free BAX or BAK from the antiapoptotic BCL-2 proteins to elicit apoptosis.Cell Research advance online publication 9 November 2010; doi:10.1038/cr.2010.149. Evidence that inhibition of BAX activation by BCL-2 involves its tight and preferential interaction with the BH3 domain of BAX.,Ku B, Liang C, Jung JU, Oh BH Cell Res. 2010 Nov 9. PMID:21060336[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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