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Crystal Structure of Rubella virus capsid protein (residues 127-277)
Structural highlights
FunctionPOLS_RUBVM 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. 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. 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 (By similarity). E1 cytoplasmic tail modulates virus release, and the tyrosines residues are critical for this function. Publication Abstract from PubMedRubella virus (RV) is a leading cause of birth defects due to infectious agents. When contracted during pregnancy, RV infection leads to severe damage in fetuses. Despite its medical importance, compared with the related alphaviruses, very little is known about the structure of RV. The RV capsid protein is an essential structural component of virions as well as a key factor in virus-host interactions. Here we describe three crystal structures of the structural domain of the RV capsid protein. The polypeptide fold of the RV capsid protomer has not been observed previously. Combining the atomic structure of the RV capsid protein with the cryoelectron tomograms of RV particles established a low-resolution structure of the virion. Mutational studies based on this structure confirmed the role of amino acid residues in the capsid that function in the assembly of infectious virions. Rubella virus capsid protein structure and its role in virus assembly and infection.,Mangala Prasad V, Willows SD, Fokine A, Battisti AJ, Sun S, Plevka P, Hobman TC, Rossmann MG Proc Natl Acad Sci U S A. 2013 Nov 26. PMID:24282305[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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