Multiple capsid protein binding sites mediate selective packaging of the alphavirus genomic RNA

Rebecca S. Brown, Dimitrios G. Anastasakis, Markus Hafner, Margaret Kielian

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


The alphavirus capsid protein (Cp) selectively packages genomic RNA (gRNA) into the viral nucleocapsid to produce infectious virus. Using photoactivatable ribonucleoside crosslinking and an innovative biotinylated Cp retrieval method, here we comprehensively define binding sites for Semliki Forest virus (SFV) Cp on the gRNA. While data in infected cells demonstrate Cp binding to the proposed genome packaging signal (PS), mutagenesis experiments show that PS is not required for production of infectious SFV or Chikungunya virus. Instead, we identify multiple Cp binding sites that are enriched on gRNA-specific regions and promote infectious SFV production and gRNA packaging. Comparisons of binding sites in cytoplasmic vs. viral nucleocapsids demonstrate that budding causes discrete changes in Cp-gRNA interactions. Notably, Cp’s top binding site is maintained throughout virus assembly, and specifically binds and assembles with Cp into core-like particles in vitro. Together our data suggest a model for selective alphavirus genome recognition and assembly.

Original languageEnglish (US)
Article number4693
JournalNature communications
Issue number1
StatePublished - Dec 1 2020

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)


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