5vsm
From Proteopedia
Crystal structure of viperin with bound [4Fe-4S] cluster, 5'-deoxyadenosine, and L-methionine
Structural highlights
Function[RSAD2_MOUSE] Interferon-inducible iron-sulfur (4FE-4S) cluster-binding antiviral protein which plays a major role in the cell antiviral state induced by type I and type II interferon. Can inhibit a wide range of viruses, including west Nile virus (WNV), dengue virus, sindbis virus, influenza A virus, sendai virus and vesicular stomatitis virus (VSV). Displays antiviral activity against influenza A virus by inhibiting the budding of the virus from the plasma membrane by disturbing the lipid rafts. This is accomplished, at least in part, through binding and inhibition of the enzyme farnesyl diphosphate synthase (FPPS), which is essential for the biosynthesis of isoprenoid-derived lipids. Promotes TLR7 and TLR9-dependent production of IFN-beta production in plasmacytoid dendritic cells (pDCs) by facilitating Lys-63'-linked ubiquitination of IRAK1. Plays a role in CD4+ T-cells activation and differentiation. Facilitates T-cell receptor (TCR)-mediated GATA3 activation and optimal T-helper 2 (Th2) cytokine production by modulating NFKB1 and JUNB activities. Can inhibit secretion of soluble proteins.[1] [2] [3] [4] Publication Abstract from PubMedViperin is an IFN-inducible radical S-adenosylmethionine (SAM) enzyme that inhibits viral replication. We determined crystal structures of an anaerobically prepared fragment of mouse viperin (residues 45-362) complexed with S-adenosylhomocysteine (SAH) or 5'-deoxyadenosine (5'-dAdo) and l-methionine (l-Met). Viperin contains a partial (betaalpha)6-barrel fold with a disordered N-terminal extension (residues 45-74) and a partially ordered C-terminal extension (residues 285-362) that bridges the partial barrel to form an overall closed barrel structure. Cys84, Cys88, and Cys91 located after the first beta-strand bind a [4Fe-4S] cluster. The active site architecture of viperin with bound SAH (a SAM analog) or 5'-dAdo and l-Met (SAM cleavage products) is consistent with the canonical mechanism of 5'-deoxyadenosyl radical generation. The viperin structure, together with sequence alignments, suggests that vertebrate viperins are highly conserved and that fungi contain a viperin-like ortholog. Many bacteria and archaebacteria also express viperin-like enzymes with conserved active site residues. Structural alignments show that viperin is similar to several other radical SAM enzymes, including the molybdenum cofactor biosynthetic enzyme MoaA and the RNA methyltransferase RlmN, which methylates specific nucleotides in rRNA and tRNA. The viperin putative active site contains several conserved positively charged residues, and a portion of the active site shows structural similarity to the GTP-binding site of MoaA, suggesting that the viperin substrate may be a nucleoside triphosphate of some type. Structural studies of viperin, an antiviral radical SAM enzyme.,Fenwick MK, Li Y, Cresswell P, Modis Y, Ealick SE Proc Natl Acad Sci U S A. 2017 Jun 27;114(26):6806-6811. doi:, 10.1073/pnas.1705402114. Epub 2017 Jun 12. PMID:28607080[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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