4c11
Dengue virus RNA dependent RNA polymerase with residues from the NS5 linker region
Structural highlights
FunctionPOLG_DEN3S 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. Overcomes the anti-viral effects of host EXOC1 by sequestering and degrading the latter through the proteasome degradation pathway.[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: 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] 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 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] 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 1: 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] Non-structural protein 2A: Component of the viral RNA replication complex that functions in virion assembly and antagonizes the host immune response.[UniProtKB:P17763] Serine protease subunit NS2B: Required cofactor for the serine protease function of NS3. May have membrane-destabilizing activity and form viroporins (By similarity).[UniProtKB:P17763][PROSITE-ProRule:PRU00859] 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.[PROSITE-ProRule:PRU00860] Non-structural protein 4A: 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 DDX58 and MAVS. In turn, IFN-beta production is impaired.[UniProtKB:P17763][UniProtKB:Q9Q6P4] 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: 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] 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:P17763] Publication Abstract from PubMedThe dengue virus (DENV) NS5 protein comprises a N-terminal methyltransferase (MTase) and a C-terminal RNA-dependent RNA polymerase (RdRp) domain. Both enzymatic activities form attractive targets for antiviral development. Available crystal structures of NS5 fragments indicate that residues 263-271 (using the DENV serotype 3 numbering) located between the two globular domains of NS5 could be flexible. We observed that the addition of linker residues to the N-terminal end of the DENV RdRp core domain stabilizes DENV1-4 proteins and improves their de novo polymerase initiation activities, by enhancing the turnover of the RNA and NTP substrates. Mutation studies of linker residues also indicate their importance for viral replication. We report the structure at 2.6 A resolution of a RdRp fragment from DENV3, spanning residues 265-900 which has enhanced catalytic properties compared to the RdRp fragment (residues 272-900) reported previously. This new orthorhombic crystal form (space-group P21212,) comprises two polymerases molecules arranged as a dimer around a non-crystallographic dyad. The enzyme adopts a closed pre-initiation conformation similar to the one that was captured previously in space-group C2221 with one molecule per asymmetric unit. The structure reveals that residues 269-271 interact with the RdRp domain and suggests that residues 263-268 of the NS5 protein from DENV3 are the major contributors to the flexibility between its MTase and RdRp domains. Together, these results should inform the screening and development of antiviral inhibitors directed against the DENV RdRp. A crystal structure of the Dengue virus NS5 polymerase delineates inter-domain amino acids residues that enhance its thermostability and de novo initiation activities.,Lim SP, Koh JH, Seh CC, Liew CW, Davidson AD, Chua LS, Chandrasekaran R, Cornvik TC, Shi PY, Lescar J J Biol Chem. 2013 Sep 11. PMID:24025331[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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