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Fitted structure of rubella virus capsid protein
Structural highlights
FunctionPOLS_RUBVT Capsid protein interacts with genomic RNA and assembles into icosaedric core particles. The resulting nucleocapsid eventually associates with the cytoplasmic domain of E2 at the cell membrane, leading to budding and formation of mature virions. Phosphorylation negatively regulates RNA-binding activity, possibly delaying virion assembly during the viral replication phase. Capsid protein dimerizes and becomes disulfide-linked in the virion, but this interaction seems not to be important for its biological function. Modulates genomic RNA replication. Modulates subgenomic RNA synthesis by interacting with human C1QBP/SF2P32. Induces both perinuclear clustering of mitochondria and the formation of electron-dense intermitochondrial plaques, both hallmarks of rubella virus infected cells. Induces apoptosis when expressed in transfected cells (By similarity). E2 envelope glycoprotein is responsible for viral attachment to target host cell, by binding to the cell receptor. Its transport to the plasma membrane depends on interaction with E1 protein (By similarity). E1 envelope glycoprotein is a class II viral fusion protein. Fusion activity is inactive as long as E1 is bound to E2 in mature virion. After virus attachment to target cell and clathrin-mediated endocytosis, acidification of the endosome would induce dissociation of E1/E2 heterodimer and concomitant trimerization of the E1 subunits. This E1 homotrimer is fusion active, and promotes release of viral nucleocapsid in cytoplasm after endosome and viral membrane fusion. E1 cytoplasmic tail modulates virus release, and the tyrosines residues are critical for this function (By similarity). Publication Abstract from PubMedViral infections during pregnancy are a significant cause of infant morbidity and mortality. Of these, rubella virus infection is a well-substantiated example that leads to miscarriages or severe fetal defects. However, structural information about the rubella virus has been lacking due to the pleomorphic nature of the virions. Here we report a helical structure of rubella virions using cryo-electron tomography. Sub-tomogram averaging of the surface spikes established the relative positions of the viral glycoproteins, which differed from the earlier icosahedral models of the virus. Tomographic analyses of in vitro assembled nucleocapsids and virions provide a template for viral assembly. Comparisons of immature and mature virions show large rearrangements in the glycoproteins that may be essential for forming the infectious virions. These results present the first known example of a helical membrane-enveloped virus, while also providing a structural basis for its assembly and maturation pathway. Assembly, maturation and three-dimensional helical structure of the teratogenic rubella virus.,Mangala Prasad V, Klose T, Rossmann MG PLoS Pathog. 2017 Jun 2;13(6):e1006377. doi: 10.1371/journal.ppat.1006377., eCollection 2017 Jun. PMID:28575072[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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