title: The picobirnavirus crystal structure provides functional insights into virion assembly and cell entry.
abstract: Double-stranded (ds) RNA virus particles are organized around a central icosahedral core capsid made of 120 identical subunits. This core capsid is unable to invade cells from outside, and animal dsRNA viruses have acquired surrounding capsid layers that are used to deliver a transcriptionally active core particle across the membrane during cell entry. In contrast, dsRNA viruses infecting primitive eukaryotes have only a simple core capsid, and as a consequence are transmitted only vertically. Here, we report the 3.4 A X-ray structure of a picobirnavirus--an animal dsRNA virus associated with diarrhoea and gastroenteritis in humans. The structure shows a simple core capsid with a distinctive icosahedral arrangement, displaying 60 two-fold symmetric dimers of a coat protein (CP) with a new 3D-fold. We show that, as many non-enveloped animal viruses, CP undergoes an autoproteolytic cleavage, releasing a post-translationally modified peptide that remains associated with nucleic acid within the capsid. Our data also show that picobirnavirus particles are capable of disrupting biological membranes in vitro, indicating that its simple 120-subunits capsid has evolved animal cell invasion properties.
authors.affiliation: Institut Pasteur, Unité de Virologie Structurale, Virology Department, CNRS URA 3015, Paris, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Duquerroy
authors.forename: Bruno
authors.initials: B
authors.lastname: Da Costa
authors.forename: Céline
authors.initials: C
authors.lastname: Henry
authors.forename: Armelle
authors.initials: A
authors.lastname: Vigouroux
authors.forename: Sonia
authors.initials: S
authors.lastname: Libersou
authors.forename: Jean
authors.initials: J
authors.lastname: Lepault
authors.forename: Jorge
authors.initials: J
authors.lastname: Navaza
authors.forename: Bernard
authors.initials: B
authors.lastname: Delmas
authors.forename: Félix A
authors.initials: FA
authors.lastname: Rey
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002213:Capsid / Q000737:chemistry / Q000648:ultrastructure; D036022:Capsid Proteins / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D019281:Dimerization; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018708:Picobirnavirus / Q000737:chemistry* / Q000502:physiology / Q000648:ultrastructure*; D011499:Protein Processing, Post-Translational; D014764:Viral Proteins / Q000737:chemistry*; D014771:Virion / Q000737:chemistry* / Q000502:physiology / Q000648:ultrastructure*; D053586:Virus Internalization
chemical_list: D036022:Capsid Proteins; D014764:Viral Proteins