| Structural highlights
Function
[STAT2_HUMAN] Signal transducer and activator of transcription that mediates signaling by type I IFNs (IFN-alpha and IFN-beta). Following type I IFN binding to cell surface receptors, Jak kinases (TYK2 and JAK1) are activated, leading to tyrosine phosphorylation of STAT1 and STAT2. The phosphorylated STATs dimerize, associate with IRF9/ISGF3G to form a complex termed ISGF3 transcription factor, that enters the nucleus. ISGF3 binds to the IFN stimulated response element (ISRE) to activate the transcription of interferon stimulated genes, which drive the cell in an antiviral state.[1] [POLG_ZIKV] Protein C: Encapsulates the genomic RNA.[UniProtKB:P17763] prM: Acts as a chaperone for envelope protein E during intracellular virion assembly by masking and inactivating envelope protein E fusion peptide. prM is matured in the last step of virion assembly, presumably to avoid catastrophic activation of the viral fusion peptide induced by the acidic pH of the trans-Golgi network. After cleavage by host furin, the pr peptide is released in the extracellular medium and small envelope protein M and envelope protein E homodimers are dissociated.[UniProtKB:P17763] Envelope protein E: Binding to host cell surface receptor is followed by virus internalization through clathrin-mediated endocytosis. Envelope protein E is subsequently involved in membrane fusion between virion and host late endosomes. Synthesized as a homodimer with prM which acts as a chaperone for envelope protein E. After cleavage of prM, envelope protein E dissociate from small envelope protein M and homodimerizes.[UniProtKB:P17763] Non-structural protein 1: Involved in virus replication and regulation of the innate immune response.[UniProtKB:P17763] Non-structural protein 2A: May be involved viral RNA replication and capsid assembly.[UniProtKB:P09732] Non-structural protein 4A: Induces host endoplasmic reticulum membrane rearrangements leading to the formation of virus-induced membranous vesicles hosting the dsRNA and polymerase, functioning as a replication complex. NS4A might also regulate the ATPase activity of the helicase region of Serine protease NS3 chain.[UniProtKB:P17763] Peptide 2k: Functions as a signal peptide for NS4B and is required for the interferon antagonism activity of the latter.[UniProtKB:P17763] Non-structural protein 4B: Inhibits interferon (IFN)-induced host STAT1 phosphorylation and nuclear translocation, thereby preventing the establishment of cellular antiviral state by blocking the IFN-alpha/beta pathway.[UniProtKB:P17763]
Publication Abstract from PubMed
Suppressing cellular signal transducers of transcription 2 (STAT2) is a common strategy that viruses use to establish infections, yet the detailed mechanism remains elusive, owing to a lack of structural information about the viral-cellular complex involved. Here, we report the cryo-EM and crystal structures of human STAT2 (hSTAT2) in complex with the non-structural protein 5 (NS5) of Zika virus (ZIKV) and dengue virus (DENV), revealing two-pronged interactions between NS5 and hSTAT2. First, the NS5 methyltransferase and RNA-dependent RNA polymerase (RdRP) domains form a conserved interdomain cleft harboring the coiled-coil domain of hSTAT2, thus preventing association of hSTAT2 with interferon regulatory factor 9. Second, the NS5 RdRP domain also binds the amino-terminal domain of hSTAT2. Disruption of these ZIKV NS5-hSTAT2 interactions compromised NS5-mediated hSTAT2 degradation and interferon suppression, and viral infection under interferon-competent conditions. Taken together, these results clarify the mechanism underlying the functional antagonism of STAT2 by both ZIKV and DENV.
Structural basis for STAT2 suppression by flavivirus NS5.,Wang B, Thurmond S, Zhou K, Sanchez-Aparicio MT, Fang J, Lu J, Gao L, Ren W, Cui Y, Veit EC, Hong H, Evans MJ, O'Leary SE, Garcia-Sastre A, Zhou ZH, Hai R, Song J Nat Struct Mol Biol. 2020 Aug 10. pii: 10.1038/s41594-020-0472-y. doi:, 10.1038/s41594-020-0472-y. PMID:32778820[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Bluyssen HA, Levy DE. Stat2 is a transcriptional activator that requires sequence-specific contacts provided by stat1 and p48 for stable interaction with DNA. J Biol Chem. 1997 Feb 14;272(7):4600-5. PMID:9020188
- ↑ Wang B, Thurmond S, Zhou K, Sanchez-Aparicio MT, Fang J, Lu J, Gao L, Ren W, Cui Y, Veit EC, Hong H, Evans MJ, O'Leary SE, Garcia-Sastre A, Zhou ZH, Hai R, Song J. Structural basis for STAT2 suppression by flavivirus NS5. Nat Struct Mol Biol. 2020 Aug 10. pii: 10.1038/s41594-020-0472-y. doi:, 10.1038/s41594-020-0472-y. PMID:32778820 doi:http://dx.doi.org/10.1038/s41594-020-0472-y
|
