The picobirnavirus crystal structure provides functional insights into virion assembly and cell entry.
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.
Duquerroy
Stéphane
S
Institut Pasteur, Unité de Virologie Structurale, Virology Department, CNRS URA 3015, Paris, France.
Da Costa
Bruno
B
Henry
Céline
C
Vigouroux
Armelle
A
Libersou
Sonia
S
Lepault
Jean
J
Navaza
Jorge
J
Delmas
Bernard
B
Rey
Félix A
FA
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
D036022:Capsid Proteins; D014764:Viral Proteins