Structure and assembly of double-stranded RNA mycoviruses

Carlos P. Mata, Javier M. Rodríguez, Nobuhiro Suzuki, José R. Castón

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

Mycoviruses are a diverse group that includes ssRNA, dsRNA, and ssDNA viruses, with or without a protein capsid, as well as with a complex envelope. Most mycoviruses are transmitted by cytoplasmic interchange and are thought to lack an extracellular phase in their infection cycle. Structural analysis has focused on dsRNA mycoviruses, which usually package their genome in a 120-subunit T = 1 icosahedral capsid, with a capsid protein (CP) dimer as the asymmetric unit. The atomic structure is available for four dsRNA mycovirus from different families: Saccharomyces cerevisiae virus L-A (ScV-L-A), Penicillium chrysogenum virus (PcV), Penicillium stoloniferum virus F (PsV-F), and Rosellinia necatrix quadrivirus 1 (RnQV1). Their capsids show structural variations of the same framework, with asymmetric or symmetric CP dimers respectively for ScV-L-A and PsV-F, dimers of similar domains of a single CP for PcV, or of two different proteins for RnQV1. The CP dimer is the building block, and assembly proceeds through dimers of dimers or pentamers of dimers, in which the genome is packed as ssRNA by interaction with CP and/or viral polymerase. These capsids remain structurally undisturbed throughout the viral cycle. The T = 1 capsid participates in RNA synthesis, organizing the viral polymerase (1–2 copies) and a single loosely packaged genome segment. It also acts as a molecular sieve, to allow the passage of viral transcripts and nucleotides, but to prevent triggering of host defense mechanisms. Due to the close mycovirus-host relationship, CP evolved to allocate peptide insertions with enzyme activity, as reflected in a rough outer capsid surface.

Original languageEnglish
Title of host publicationAdvances in Virus Research
EditorsMargaret Kielian, Thomas C. Mettenleiter, Marilyn J. Roossinck
PublisherAcademic Press Inc.
Pages213-247
Number of pages35
ISBN (Print)9780128207611
DOIs
Publication statusPublished - Jan 2020
Externally publishedYes

Publication series

NameAdvances in Virus Research
Volume108
ISSN (Print)0065-3527
ISSN (Electronic)1557-8399

Keywords

  • Capsid assembly
  • Capsid protein
  • PcV
  • PsV-F
  • RnQV1
  • ScV-L-A
  • Virus evolution
  • dsRNA mycovirus

ASJC Scopus subject areas

  • Virology
  • Infectious Diseases

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