5o36
Japanese encephalitis virus non-structural protein 1' C-terminal domain
Structural highlights
FunctionPOLS_JAEV1 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 (By similarity). Inhibits the integrated stress response (ISR) in the infected cell by binding to host CAPRIN1 (By similarity).[UniProtKB:P0DOH8][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] May play a role in neuroinvasiveness.[UniProtKB:P0DOH8] Publication Abstract from PubMedJapanese encephalitis virus (JEV) is a mosquito-transmitted Flavivirus that is closely related to other emerging viral pathogens including dengue, West Nile (WNV) and Zika viruses. JEV infection can result in meningitis and encephalitis, which in severe cases cause permanent brain damage and death. JEV occurs predominantly in rural areas throughout Southeast Asia, the Pacific islands and the Far East, causing around 68,000 cases worldwide each year. In this study, we present a 2.1 A resolution crystal structure of the C-terminal beta-ladder domain of JEV non-structural protein 1 (NS1-C). The surface charge distribution of JEV NS1-C is similar to WNV and ZIKV but differs form DENV. Analysis of the JEV NS1-C structure, with in silico molecular dynamics simulation and experimental solution small angle X-ray scattering, indicates extensive loop flexibility on the exterior of the protein. This, together with the surface charge distribution, indicates flexibility influences the protein-protein interactions that govern pathogenicity. These factors also affect the interaction of NS1 with the monoclonal antibody, 22NS1, which is protective against West Nile virus infection. Liposome and heparin binding assays indicate that only the N-terminal region of NS1 mediates interaction with membranes, and that sulfate binding sites common to NS1 structures are not glycosaminoglycan binding interfaces. This study highlights several differences between flavivirus NS1 proteins and contributes to our understanding of their structure-pathogenic function relationships.IMPORTANCE JEV is a major cause of viral encephalitis in Asia. Despite extensive vaccination, epidemics still occur. Non-structural protein 1 (NS1) plays a role in viral replication and, because it is secreted, it can exhibit a wide range of interations with host proteins. NS1 sequence and protein folds are conserved within the Flavivirus genus, but variations in NS1 protein-protein interactions among viruses likely contribute to differences in pathogenesis. Here, we compared characteristics of the the C-terminal beta-ladder domain of NS1 between flaviviruses including surface charge, loop flexibility, epitope cross-reactivity, membrane adherence, and glycosaminoglycan binding. These structural features are central to NS1 functionality and may provide insight into the development of diagnostic tests and therapeutics. Structural study of the C-terminal domain of non-structural protein 1 from Japanese encephalitis virus.,Poonsiri T, Wright GSA, Diamond MS, Turtle L, Solomon T, Antonyuk SV J Virol. 2018 Jan 17. pii: JVI.01868-17. doi: 10.1128/JVI.01868-17. PMID:29343583[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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