5kdm
From Proteopedia
Crystal structure of EBV tegument protein BNRF1 in complex with histone chaperone DAXX and histones H3.3-H4
Structural highlights
Function[MTP_EBVA8] Tegument protein that plays a role in the inhibition of host intrinsic defenses to promote viral early gene activation. Interacts with host DAXX and thereby disrupts the complex between DAXX and ATRX. Suppresses the DAXX-ATRX dependent deposition of histone H3.3 on viral chromatin allowing viral transcription. May also play a role in virus entry at attachment or membrane fusion steps.[UniProtKB:P03179] [DAXX_HUMAN] Transcription corepressor known to repress transcriptional potential of several sumoylated transcription factors. Acts as an adapter protein in a MDM2-DAXX-USP7 complex by regulating the RING-finger E3 ligase MDM2 ubiquitination activity. Under non-stress condition, in association with the deubiquitinating USP7, prevents MDM2 self-ubiquitination and enhances the intrinsic E3 ligase activity of MDM2 towards TP53, thereby promoting TP53 ubiquitination and subsequent proteasomal degradation. Upon DNA damage, its association with MDM2 and USP7 is disrupted, resulting in increased MDM2 autoubiquitination and consequently, MDM2 degradation, which leads to TP53 stabilization. Proposed to mediate activation of the JNK pathway and apoptosis via MAP3K5 in response to signaling from TNFRSF6 and TGFBR2. Interaction with HSPB1/HSP27 may prevent interaction with TNFRSF6 and MAP3K5 and block DAXX-mediated apoptosis. In contrast, in lymphoid cells JNC activation and TNFRSF6-mediated apoptosis may not involve DAXX. Seems to regulate transcription in PML/POD/ND10 nuclear bodies together with PML and may influence TNFRSF6-dependent apoptosis thereby. Down-regulates basal and activated transcription. Seems to act as a transcriptional corepressor and inhibits PAX3 and ETS1 through direct protein-protein interaction. Modulates PAX5 activity. Its transcription repressor activity is modulated by recruiting it to subnuclear compartments like the nucleolus or PML/POD/ND10 nuclear bodies through interactions with MCSR1 and PML, respectively.[1] [2] [3] [4] Publication Abstract from PubMedThe histone H3.3 chaperone DAXX is implicated in formation of heterochromatin and transcription silencing, especially for newly infecting DNA virus genomes entering the nucleus. Epstein-Barr virus (EBV) can efficiently establish stable latent infection as a chromatinized episome in the nucleus of infected cells. The EBV tegument BNRF1 is a DAXX-interacting protein required for the establishment of selective viral gene expression during latency. Here we report the structure of BNRF1 DAXX-interaction domain (DID) in complex with DAXX histone-binding domain (HBD) and histones H3.3-H4. BNRF1 DID contacts DAXX HBD and histones through non-conserved loops. The BNRF1-DAXX interface is responsible for BNRF1 localization to PML-nuclear bodies typically associated with host-antiviral resistance and transcriptional repression. Paradoxically, the interface is also required for selective transcription activation of viral latent cycle genes required for driving B-cell proliferation. These findings reveal molecular details of virus reprogramming of an antiviral histone chaperone to promote viral latency and cellular immortalization. Structural basis underlying viral hijacking of a histone chaperone complex.,Huang H, Deng Z, Vladimirova O, Wiedmer A, Lu F, Lieberman PM, Patel DJ Nat Commun. 2016 Sep 1;7:12707. doi: 10.1038/ncomms12707. PMID:27581705[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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