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Features of Reovirus Outer-Capsid Protein mu1 Revealed by Electron and Image Reconstruction of the virion at 7.0-A ResolutionFeatures of Reovirus Outer-Capsid Protein mu1 Revealed by Electron and Image Reconstruction of the virion at 7.0-A Resolution
Structural highlights
Function[LMBD1_REOVL] Inner capsid (core) component. Displays NTPase, RNA 5'-triphosphatase (RTPase) and RNA helicase activities and probably participates in transcription of the viral genome. Helicase activity might be involved in unwinding or reannealing dsRNA during RNA synthesis. RTPase enzymatic activity represents the first step in RNA capping, which yields a 5'-diphosphorylated plus-strand RNA (By similarity). [MU1_REOVL] Major outer capsid protein involved in host cell membrane penetration. In the endocytic compartment, outer-capsid protein sigma-3 is removed by cathepsin proteases, which exposes the viral membrane-penetration protein mu-1. Both myristoylated peptides mu-1N and phi are released during infectious subvirion particles (ISVP) formation in the endosome. They associate with host membranes and mu-1N induces permeabilization and delivery of transcriptionally active viral particles into the host cell cytoplasm. Seems to induce apoptosis in the host cell.[1] [2] [3] [4] [5] The viral outer shell polypeptides, of which mu-1 is one, impose structural constraints that prevent elongation of nascent transcripts by the RNA-dependent RNA polymerase lambda-3.[6] [7] [8] [9] [10] [LMBD2_REOVD] Outer capsid protein involved in mRNA capping. Catalyzes the last 3 enzymatic activities for formation of the 5' cap structure on the viral plus-strand transcripts, namely the RNA guanylyltransferase, RNA-7N- and RNA-2'O-methyltransferase activities. [SIGM3_REOVL] Stimulates translation by blocking the activation of the dsRNA-dependent protein kinase EIF2AK2/PKR, thereby inhibiting the host interferon response. Sigma3 prevents the activation of EIF2AK2 by competing with the kinase for dsRNA-binding (By similarity). The viral outer shell polypeptides, of which sigma-3 is one, impose structural constraints that prevent elongation of nascent transcripts by the RNA-dependent RNA polymerase lambda-3. [SIGM2_REOVL] Inner capsid (core) component. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedReovirus is a useful model for addressing the molecular basis of membrane penetration by one of the larger nonenveloped animal viruses. We now report the structure of the reovirus virion at approximately 7.0 A resolution as obtained by electron cryomicroscopy and three-dimensional image reconstruction. Several features of the myristoylated outer capsid protein mu1, not seen in a previous X-ray crystal structure of the mu1-sigma3 heterohexamer, are evident in the virion. These features appear to be important for stabilizing the outer capsid, regulating the conformational changes in mu1 that accompany perforation of target membranes, and contributing directly to membrane penetration during cell entry. Features of reovirus outer capsid protein mu1 revealed by electron cryomicroscopy and image reconstruction of the virion at 7.0 Angstrom resolution.,Zhang X, Ji Y, Zhang L, Harrison SC, Marinescu DC, Nibert ML, Baker TS Structure. 2005 Oct;13(10):1545-57. PMID:16216585[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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