title: Combined structural, biochemical and cellular evidence demonstrates that both FGDF motifs in alphavirus nsP3 are required for efficient replication.
abstract: Recent findings have highlighted the role of the Old World alphavirus non-structural protein 3 (nsP3) as a host defence modulator that functions by disrupting stress granules, subcellular phase-dense RNA/protein structures formed upon environmental stress. This disruption mechanism was largely explained through nsP3-mediated recruitment of the host G3BP protein via two tandem FGDF motifs. Here, we present the 1.9 Å resolution crystal structure of the NTF2-like domain of G3BP-1 in complex with a 25-residue peptide derived from Semliki Forest virus nsP3 (nsP3-25). The structure reveals a poly-complex of G3BP-1 dimers interconnected through the FGDF motifs in nsP3-25. Although in vitro and in vivo binding studies revealed a hierarchical interaction of the two FGDF motifs with G3BP-1, viral growth curves clearly demonstrated that two intact FGDF motifs are required for efficient viral replication. Chikungunya virus nsP3 also binds G3BP dimers via a hierarchical interaction, which was found to be critical for viral replication. These results highlight a conserved molecular mechanism in host cell modulation.
authors.affiliation: Science for Life Laboratory, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden Department of Infectious Diseases, Karolinska University Hospital, Solna, Stockholm, Sweden.
authors.forename: Tim
authors.initials: T
authors.lastname: Schulte
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Lifeng
authors.initials: L
authors.lastname: Liu
authors.affiliation: Division of Rheumatology, Immunology and Allergy, Harvard Medical School and Brigham and Women's Hospital, Smith 652; 1 Jimmy Fund Way, Boston, MA 02115, USA.
authors.forename: Marc D
authors.initials: MD
authors.lastname: Panas
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Bastian
authors.initials: B
authors.lastname: Thaa
authors.affiliation: Science for Life Laboratory, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden Department of Infectious Diseases, Karolinska University Hospital, Solna, Stockholm, Sweden.
authors.forename: Nicole
authors.initials: N
authors.lastname: Dickson
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Götte
authors.affiliation: Science for Life Laboratory, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden Department of Infectious Diseases, Karolinska University Hospital, Solna, Stockholm, Sweden adnane.achour@ki.se.
authors.forename: Adnane
authors.initials: A
authors.lastname: Achour
authors.affiliation: Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden gerald.mcinerney@ki.se.
authors.forename: Gerald M
authors.identifier: 0000-0003-2257-7241
authors.initials: GM
authors.lastname: McInerney
mesh_terms: D020816:Amino Acid Motifs; D002460:Cell Line; D002646:Chikungunya virus / Q000378:metabolism / Q000502:physiology; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D004265:DNA Helicases / Q000737:chemistry* / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D008958:Models, Molecular; D000075223:Poly-ADP-Ribose Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D020365:RNA Helicases / Q000737:chemistry* / Q000378:metabolism*; D000067776:RNA Recognition Motif Proteins / Q000737:chemistry* / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D012672:Semliki forest virus / Q000378:metabolism / Q000502:physiology*; D017361:Viral Nonstructural Proteins / Q000737:chemistry* / Q000378:metabolism*; D014779:Virus Replication
chemical_list: C414175:Nsp3 protein, semliki forest virus; D000075223:Poly-ADP-Ribose Binding Proteins; D000067776:RNA Recognition Motif Proteins; D016601:RNA-Binding Proteins; D017361:Viral Nonstructural Proteins; D004265:DNA Helicases; C116070:G3BP1 protein, human; D020365:RNA Helicases
keywords: innate immunity; protein structure–function; stress response; virus–host interaction