8wbh
From Proteopedia
CryoEM structure of non-structural protein 1 tetramer from Japanese encephalitis virus
Structural highlights
FunctionQ82919_9FLAV 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.[ARBA:ARBA00035620] Component of the viral RNA replication complex that functions in virion assembly and antagonizes the host alpha/beta interferon antiviral response.[ARBA:ARBA00035615] Functions as a signal peptide for NS4B and is required for the interferon antagonism activity of the latter.[ARBA:ARBA00003504] Inhibits RNA silencing by interfering with host Dicer.[ARBA:ARBA00035616] 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).[ARBA:ARBA00035605] May play a role in virus budding. Exerts cytotoxic effects by activating a mitochondrial apoptotic pathway through M ectodomain. May display a viroporin activity.[ARBA:ARBA00035609] 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.[ARBA:ARBA00035602] Publication Abstract from PubMedFlaviviruses encode a conserved, membrane-associated nonstructural protein 1 (NS1) with replication and immune evasion functions. The current knowledge of secreted NS1 (sNS1) oligomers is based on several low-resolution structures, thus hindering the development of drugs and vaccines against flaviviruses. Here, we revealed that recombinant sNS1 from flaviviruses exists in a dynamic equilibrium of dimer-tetramer-hexamer states. Two DENV4 hexameric NS1 structures and several tetrameric NS1 structures from multiple flaviviruses were solved at atomic resolution by cryo-EM. The stacking of the tetrameric NS1 and hexameric NS1 is facilitated by the hydrophobic beta-roll and connector domains. Additionally, a triacylglycerol molecule located within the central cavity may play a role in stabilizing the hexamer. Based on differentiated interactions between the dimeric NS1, two distinct hexamer models (head-to-head and side-to-side hexamer) and the step-by-step assembly mechanisms of NS1 dimer into hexamer were proposed. We believe that our study sheds light on the understanding of the NS1 oligomerization and contributes to NS1-based therapies. The step-by-step assembly mechanism of secreted flavivirus NS1 tetramer and hexamer captured at atomic resolution.,Pan Q, Jiao H, Zhang W, Chen Q, Zhang G, Yu J, Zhao W, Hu H Sci Adv. 2024 May 3;10(18):eadm8275. doi: 10.1126/sciadv.adm8275. Epub 2024 May , 1. PMID:38691607[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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