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Crystal structure of the Zika virus NS3 helicase (apo form)Crystal structure of the Zika virus NS3 helicase (apo form)
Structural highlights
FunctionPOLG_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 PubMedZika virus (ZIKV), a positive-strand RNA virus belonging to the Flavivirus genus, has become an urgent public health concern since recent outbreaks worldwide. Its genome replication is facilitated by the viral NS3 protein bearing helicase function. The NS3 helicase uses energy derived from adenosine triphosphate (ATP) hydrolysis to unwind RNA duplexed regions. Structural studies of the flavivirus NS3 helicases have suggested a conserved mechanism of ATP hydrolysis. However, the process of the reactant water replenishment, a key part of the hydrolysis cycle, remains elusive. Here, we report two high-resolution crystal structures of ZIKV NS3 helicase in complex with adenosine diphosphate (ADP) and Mn(2+), one with the reactant water already loaded as previously observed and the other with the water molecule still in a loading state. These data suggest that the reactant water replenishment can occur between the release of phosphate and the release of ADP and improves the structural basis of the NS3 ATP hydrolysis cycle. Crystallographic Snapshots of the Zika Virus NS3 Helicase Help Visualize the Reactant Water Replenishment.,Fang J, Jing X, Lu G, Xu Y, Gong P ACS Infect Dis. 2019 Feb 8;5(2):177-183. doi: 10.1021/acsinfecdis.8b00214. Epub, 2019 Jan 28. PMID:30672289[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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