5fcg
Crystal structure of Bcl-2 in complex with HBx-BH3 motif
Structural highlights
DiseaseBCL2_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. FunctionBCL2_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] Publication Abstract from PubMedHBx is a hepatitis B virus protein that is required for viral infectivity and replication. Anti-apoptotic Bcl-2 family members are thought to be among the important host targets of HBx. However, the structure and function of HBx are poorly understood and the molecular mechanism of HBx-induced carcinogenesis remains unknown. In this study, we report biochemical and structural characterization of HBx. The recombinant HBx protein contains metal ions, in particular iron and zinc. A BH3-like motif in HBx (residues 110-135) binds Bcl-2 with a dissociation constant of approximately 193 muM, which is drastically lower than that for a canonical BH3 motif from Bim or Bad. Structural analysis reveals that, similar to other BH3 motifs, the BH3-like motif of HBx adopts an amphipathic alpha-helix and binds the conserved BH3-binding groove on Bcl-2. Unlike the helical Bim or Bad BH3 motif, the C-terminal portion of the bound HBx BH3-like motif has an extended conformation and makes considerably fewer interactions with Bcl-2. These observations suggest that HBx may modulate Bcl-2 function in a way that is different from that of the classical BH3-only proteins. Structural and biochemical analysis of Bcl-2 interaction with the hepatitis B virus protein HBx.,Jiang T, Liu M, Wu J, Shi Y Proc Natl Acad Sci U S A. 2016 Feb 23;113(8):2074-9. doi:, 10.1073/pnas.1525616113. Epub 2016 Feb 8. PMID:26858413[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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