3q7b
Exonuclease domain of Lassa virus nucleoproteinExonuclease domain of Lassa virus nucleoprotein
Structural highlights
Function[NCAP_LASSJ] Encapsidates the genome, protecting it from nucleases. The encapsidated genomic RNA is termed the nucleocapsid (NC). Serves as template for viral transcription and replication. The increased presence of protein N in host cell does not seem to trigger the switch from transcription to replication as observed in other negative strain RNA viruses. Disables the host innate defense by interfering with beta interferon (IFN-beta) production. Strongly inhibits the nuclear translocation of IRF3, a protein involved in IFN activation pathway. Also inhibits the activation of IFN-beta and IRF3-dependent promoters (By similarity). Publication Abstract from PubMedLassa fever virus, a member of the family Arenaviridae, is a highly endemic category A pathogen that causes 300,000-500,000 infections per year in Western Africa. The arenaviral nucleoprotein NP has been implicated in suppression of the host innate immune system, but the mechanism by which this occurs has remained elusive. Here we present the crystal structure at 1.5 A of the immunosuppressive C-terminal portion of Lassa virus NP and illustrate that, unexpectedly, its 3D fold closely mimics that of the DEDDh family of exonucleases. Accompanying biochemical experiments illustrate that NP indeed has a previously unknown, bona fide exonuclease activity, with strict specificity for double-stranded RNA substrates. We further demonstrate that this exonuclease activity is essential for the ability of NP to suppress translocation of IFN regulatory factor 3 and block activation of the innate immune system. Thus, the nucleoprotein is a viral exonuclease with anti-immune activity, and this work provides a unique opportunity to combat arenaviral infections. Structure of the Lassa virus nucleoprotein reveals a dsRNA-specific 3' to 5' exonuclease activity essential for immune suppression.,Hastie KM, Kimberlin CR, Zandonatti MA, Macrae IJ, Saphire EO Proc Natl Acad Sci U S A. 2011 Jan 24. PMID:21262835[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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