title: Sequestration of G3BP coupled with efficient translation inhibits stress granules in Semliki Forest virus infection.
abstract: Dynamic, mRNA-containing stress granules (SGs) form in the cytoplasm of cells under environmental stresses, including viral infection. Many viruses appear to employ mechanisms to disrupt the formation of SGs on their mRNAs, suggesting that they represent a cellular defense against infection. Here, we report that early in Semliki Forest virus infection, the C-terminal domain of the viral nonstructural protein 3 (nsP3) forms a complex with Ras-GAP SH3-domain-binding protein (G3BP) and sequesters it into viral RNA replication complexes in a manner that inhibits the formation of SGs on viral mRNAs. A viral mutant carrying a C-terminal truncation of nsP3 induces more persistent SGs and is attenuated for propagation in cell culture. Of importance, we also show that the efficient translation of viral mRNAs containing a translation enhancer sequence also contributes to the disassembly of SGs in infected cells. Furthermore, we show that the nsP3/G3BP interaction also blocks SGs induced by other stresses than virus infection. This is one of few described viral mechanisms for SG disruption and underlines the role of SGs in antiviral defense.
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
authors.forename: Marc D
authors.initials: MD
authors.lastname: Panas
authors.forename: Margus
authors.initials: M
authors.lastname: Varjak
authors.forename: Aleksei
authors.initials: A
authors.lastname: Lulla
authors.forename: Kai Er
authors.initials: KE
authors.lastname: Eng
authors.forename: Andres
authors.initials: A
authors.lastname: Merits
authors.forename: Gunilla B
authors.initials: GB
authors.lastname: Karlsson Hedestam
authors.forename: Gerald M
authors.initials: GM
authors.lastname: McInerney
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D003594:Cytoplasmic Granules / Q000378:metabolism* / Q000821:virology; D004265:DNA Helicases; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D015151:Immunoblotting; D051379:Mice; D018613:Microscopy, Confocal; D009154:Mutation; D000075223:Poly-ADP-Ribose Binding Proteins; D011485:Protein Binding; D014176:Protein Biosynthesis; D020365:RNA Helicases; D000067776:RNA Recognition Motif Proteins; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012672:Semliki forest virus / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D013312:Stress, Physiological; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C574606:G3BP2 protein, human; C414175:Nsp3 protein, semliki forest virus; D000075223:Poly-ADP-Ribose Binding Proteins; D000067776:RNA Recognition Motif Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D017361:Viral Nonstructural Proteins; D049452:Green Fluorescent Proteins; D004265:DNA Helicases; C116070:G3BP1 protein, human; D020365:RNA Helicases