4u2x
From Proteopedia
Ebola virus VP24 in complex with Karyopherin alpha 5 C-terminus
Structural highlights
Function[VP24_EBOZM] Prevents the establishment of cellular antiviral state by blocking the interferon-alpha/beta (IFN-alpha/beta) and IFN-gamma signaling pathways. Blocks the IFN-induced nuclear accumulation of host phosphorylated STAT1, by interacting with the STAT1-binding region of host importin alpha-1/KPNA1 protein, thereby inhibiting the latter. Without the activity of this protein, activated STAT1 would not enter the nucleus and be unable to activate IFN-induced genes. Plays a role in assembly of viral nucleocapsid and virion budding. May act as a minor matrix protein that plays a role in assembly of viral nucleocapsid and virion budding.[1] [2] [3] [4] [IMA6_HUMAN] Functions in nuclear protein import as an adapter protein for nuclear receptor KPNB1. Binds specifically and directly to substrates containing either a simple or bipartite NLS motif. Docking of the importin/substrate complex to the nuclear pore complex (NPC) is mediated by KPNB1 through binding to nucleoporin FxFG repeats and the complex is subsequently translocated through the pore by an energy requiring, Ran-dependent mechanism. At the nucleoplasmic side of the NPC, Ran binds to importin-beta and the three components separate and importin-alpha and -beta are re-exported from the nucleus to the cytoplasm where GTP hydrolysis releases Ran from importin. The directionality of nuclear import is thought to be conferred by an asymmetric distribution of the GTP- and GDP-bound forms of Ran between the cytoplasm and nucleus. Mediates nuclear import of STAT1 homodimers and STAT1/STAT2 heterodimers by recognizing non-classical NLSs of STAT1 and STAT2 through ARM repeats 8-9. Recognizes influenza A virus nucleoprotein through ARM repeat 7-9 In vitro, mediates the nuclear import of human cytomegalovirus UL84 by recognizing a non-classical NLS. Publication Abstract from PubMedDuring antiviral defense, interferon (IFN) signaling triggers nuclear transport of tyrosine-phosphorylated STAT1 (PY-STAT1), which occurs via a subset of karyopherin alpha (KPNA) nuclear transporters. Many viruses, including Ebola virus, actively antagonize STAT1 signaling to counteract the antiviral effects of IFN. Ebola virus VP24 protein (eVP24) binds KPNA to inhibit PY-STAT1 nuclear transport and render cells refractory to IFNs. We describe the structure of human KPNA5 C terminus in complex with eVP24. In the complex, eVP24 recognizes a unique nonclassical nuclear localization signal (NLS) binding site on KPNA5 that is necessary for efficient PY-STAT1 nuclear transport. eVP24 binds KPNA5 with very high affinity to effectively compete with and inhibit PY-STAT1 nuclear transport. In contrast, eVP24 binding does not affect the transport of classical NLS cargo. Thus, eVP24 counters cell-intrinsic innate immunity by selectively targeting PY-STAT1 nuclear import while leaving the transport of other cargo that may be required for viral replication unaffected. Ebola Virus VP24 Targets a Unique NLS Binding Site on Karyopherin Alpha 5 to Selectively Compete with Nuclear Import of Phosphorylated STAT1.,Xu W, Edwards MR, Borek DM, Feagins AR, Mittal A, Alinger JB, Berry KN, Yen B, Hamilton J, Brett TJ, Pappu RV, Leung DW, Basler CF, Amarasinghe GK Cell Host Microbe. 2014 Aug 13;16(2):187-200. doi: 10.1016/j.chom.2014.07.008. PMID:25121748[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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Categories: Ebov-may | Human | Amarasinghe, G | Borek, D | Leung, D | Xu, W | Evp24 | Immune antagonist | Importin alpha6 | Viral protein
