7cbp
From Proteopedia
CryoEM structure of Zika virus with Fab at 4.1 Angstrom
Structural highlights
Function[POLG_ZIKVF] Capsid protein C: 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.[UniProtKB:P17763] Capsid protein C: Inhibits RNA silencing by interfering with host Dicer.[UniProtKB:P03314] Peptide pr: 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] Protein prM: Plays a role in host immune defense modulation and protection of envelope protein E during virion synthesis. PrM-E cleavage is ineficient, and immature prM-E proteins could have an activity against host immune response. The sequence of PrM contributes to fetal microcephaly in Humans. 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 could play a role in immune evasion.[UniProtKB:P17763][1] Small envelope protein M: 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] Envelope protein E: 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 particule 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 could play a role in immune evasion.[UniProtKB:P17763] Non-structural protein 1: 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] Non-structural protein 2A: Component of the viral RNA replication complex that functions in virion assembly and antagonizes the host alpha/beta interferon antiviral response (By similarity). Disrupts adherens junction formation and thereby impairs proliferation of radial cells in both embryonic mouse cortex and human forebrain organoids (PubMed:28826723).[UniProtKB:P14335][2] Non-structural protein 2B: Required cofactor for the serine protease function of NS3.[UniProtKB:Q32ZE1] Serine protease NS3: 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 (By similarity). Leads to translation arrest when expressed ex vivo (PubMed:28592527).[UniProtKB:Q32ZE1][3] Non-structural protein 4A: Regulates the ATPase activity of the NS3 helicase activity. NS4A allows NS3 helicase to conserve energy during unwinding (By similarity). Cooperatively with NS4B suppress the Akt-mTOR pathway and lead to cellular dysregulation (PubMed:27524440). Leads to translation arrest when expressed ex vivo (PubMed:28592527).[UniProtKB:Q9Q6P4][4] [5] Peptide 2k: Functions as a signal peptide for NS4B and is required for the interferon antagonism activity of the latter. Non-structural protein 4B: 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. Inhibits STAT2 translocation in the nucleus after IFN-alpha treatment (By similarity). Cooperatively with NS4A suppress the Akt-mTOR pathway and lead to cellular dysregulation (PubMed:27524440).[UniProtKB:Q9Q6P4][6] RNA-directed RNA polymerase NS5: 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.[UniProtKB:Q9Q6P4] Publication Abstract from PubMedZika virus (ZIKV) recently emerged as a major public health concern because it can cause fetal microcephaly and neurological disease such as the Guillain-Barre syndrome. A particularly potent class of broadly neutralizing antibodies (nAbs) targets a quaternary epitope located at the interface of two envelope proteins monomers, exposed at the surface of the mature virion. This "E-dimer-dependent epitope" (EDE), comprises the fusion loop of one monomer at the tip of domain II of E and a portion of the domains I and III of the adjacent monomer. Since this epitope largely overlaps with the binding site of the precursor membrane protein (prM) during Zika virion maturation, its molecular surface is evolutionary conserved in flaviviruses such as Dengue and Zika viruses, and can elicit antibodies that broadly neutralize various ZIKV strains. Here, we present a cryo-EM reconstruction at 4.1 A resolution of the virion bound to the antigen binding fragment (Fab) of an antibody that targets this mutationally-constrained quaternary epitope. The Fab incompletely covers the surface of the virion as it does not bind next to its 5-fold icosahedral axes. The structure reveals details of the binding mode of this potent neutralizing class of antibodies and can inform the design of immunogens and vaccines targeting this conserved epitope. A complex between the Zika virion and the Fab of a broadly cross-reactive neutralizing monoclonal antibody revealed by cryo-EM and single particle analysis at 4.1 A resolution.,Tyagi A, Ahmed T, Shi J, Bhushan S J Struct Biol X. 2020 Jun 17;4:100028. doi: 10.1016/j.yjsbx.2020.100028., eCollection 2020. PMID:32647830[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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Categories: Human | Large Structures | Zika virus | Ahmed, T | Bhushan, S | Shi, J | Tyagi, A | Fab antibody | Virus
