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Structure of Dengue virus strain 4 DIII in complex with Fab 2H12
Structural highlights
FunctionPOLG_DEN4P Plays a role in virus budding by binding to the cell membrane and gathering the viral RNA into a nucleocapsid that forms the core of a mature virus particle. During virus entry, may induce genome penetration into the host cytoplasm after hemifusion induced by the surface proteins. Can migrate to the cell nucleus where it modulates host functions. Overcomes the anti-viral effects of host EXOC1 by sequestering and degrading the latter through the proteasome degradation pathway.[UniProtKB:P17763] Inhibits RNA silencing by interfering with host Dicer.[UniProtKB:P03314] Prevents premature fusion activity of envelope proteins in trans-Golgi by binding to envelope protein E at pH6.0. After virion release in extracellular space, gets dissociated from E dimers.[UniProtKB:P17763] Acts as a chaperone for envelope protein E during intracellular virion assembly by masking and inactivating envelope protein E fusion peptide. prM is the only viral peptide matured by host furin in the trans-Golgi network probably to avoid catastrophic activation of the viral fusion activity in acidic Golgi compartment prior to virion release. prM-E cleavage is inefficient, and many virions are only partially matured. These uncleaved prM would play a role in immune evasion.[UniProtKB:P17763] May play a role in virus budding. Exerts cytotoxic effects by activating a mitochondrial apoptotic pathway through M ectodomain. May display a viroporin activity.[UniProtKB:P17763] Binds to host cell surface receptor and mediates fusion between viral and cellular membranes. Envelope protein is synthesized in the endoplasmic reticulum in the form of heterodimer with protein prM. They play a role in virion budding in the ER, and the newly formed immature particle is covered with 60 spikes composed of heterodimer between precursor prM and envelope protein E. The virion is transported to the Golgi apparatus where the low pH causes dissociation of PrM-E heterodimers and formation of E homodimers. prM-E cleavage is inefficient, and many virions are only partially matured. These uncleaved prM would play a role in immune evasion.[UniProtKB:P17763] Involved in immune evasion, pathogenesis and viral replication. Once cleaved off the polyprotein, is targeted to three destinations: the viral replication cycle, the plasma membrane and the extracellular compartment. Essential for viral replication. Required for formation of the replication complex and recruitment of other non-structural proteins to the ER-derived membrane structures. Excreted as a hexameric lipoparticle that plays a role against host immune response. Antagonizing the complement function. Binds to the host macrophages and dendritic cells. Inhibits signal transduction originating from Toll-like receptor 3 (TLR3).[UniProtKB:Q9Q6P4] Disrupts the host endothelial glycocalyx layer of host pulmonary microvascular endothelial cells, inducing degradation of sialic acid and shedding of heparan sulfate proteoglycans. NS1 induces expression of sialidases, heparanase, and activates cathepsin L, which activates heparanase via enzymatic cleavage. These effects are probably linked to the endothelial hyperpermeability observed in severe dengue disease.[UniProtKB:P17763] Component of the viral RNA replication complex that functions in virion assembly and antagonizes the host immune response.[UniProtKB:P17763] Required cofactor for the serine protease function of NS3. May have membrane-destabilizing activity and form viroporins (By similarity).[UniProtKB:P17763][PROSITE-ProRule:PRU00859] Displays three enzymatic activities: serine protease, NTPase and RNA helicase. NS3 serine protease, in association with NS2B, performs its autocleavage and cleaves the polyprotein at dibasic sites in the cytoplasm: C-prM, NS2A-NS2B, NS2B-NS3, NS3-NS4A, NS4A-2K and NS4B-NS5. NS3 RNA helicase binds RNA and unwinds dsRNA in the 3' to 5' direction.[PROSITE-ProRule:PRU00860] Regulates the ATPase activity of the NS3 helicase activity. NS4A allows NS3 helicase to conserve energy during unwinding. Plays a role in the inhibition of the host innate immune response. Interacts with host MAVS and thereby prevents the interaction between RIGI and MAVS. In turn, IFN-beta production is impaired. Interacts with host AUP1 which mediates induction of lipophagy in host cells and facilitates production of virus progeny particles (By similarity).[UniProtKB:P17763][UniProtKB:P29991][UniProtKB:Q9Q6P4] Functions as a signal peptide for NS4B and is required for the interferon antagonism activity of the latter.[UniProtKB:P17763] Induces the formation of ER-derived membrane vesicles where the viral replication takes place. 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:Q9Q6P4] Replicates the viral (+) and (-) RNA genome, and performs the capping of genomes in the cytoplasm. NS5 methylates viral RNA cap at guanine N-7 and ribose 2'-O positions. Besides its role in RNA genome replication, also prevents the establishment of cellular antiviral state by blocking the interferon-alpha/beta (IFN-alpha/beta) signaling pathway. Inhibits host TYK2 and STAT2 phosphorylation, thereby preventing activation of JAK-STAT signaling pathway (By similarity). May reduce immune responses by preventing the recruitment of the host PAF1 complex to interferon-responsive genes (By similarity).[UniProtKB:P09866][UniProtKB:P17763] Publication Abstract from PubMedDengue virus infections are still increasing at an alarming rate in tropical and subtropical countries, underlying the need for a dengue vaccine. Although it is relatively easy to generate Ab responses to dengue virus, low avidity or low concentrations of Ab may enhance infection of FcR-bearing cells with clinical impact, posing a challenge to vaccine production. In this article, we report the characterization of a mAb, 2H12, which is cross-reactive to all four serotypes in the dengue virus group. Crystal structures of 2H12-Fab in complex with domain III of the envelope protein from three dengue serotypes have been determined. 2H12 binds to the highly conserved AB loop of domain III of the envelope protein that is poorly accessible in the mature virion. 2H12 neutralization varied between dengue serotypes and strains; in particular, dengue serotype 2 was not neutralized. Because the 2H12-binding epitope was conserved, this variation in neutralization highlights differences between dengue serotypes and suggests that significant conformational changes in the virus must take place for Ab binding. Surprisingly, 2H12 facilitated little or no enhancement of infection. These data provide a structural basis for understanding Ab neutralization and enhancement of infection, which is crucial for the development of future dengue vaccines. Structural Analysis of a Dengue Cross-Reactive Antibody Complexed with Envelope Domain III Reveals the Molecular Basis of Cross-Reactivity.,Midgley CM, Flanagan A, Tran HB, Dejnirattisai W, Chawansuntati K, Jumnainsong A, Wongwiwat W, Duangchinda T, Mongkolsapaya J, Grimes JM, Screaton GR J Immunol. 2012 May 15;188(10):4971-9. Epub 2012 Apr 9. PMID:22491255[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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