Length of encapsidated cargo impacts stability and structure of in vitro assembled alphavirus core-like particles

Vamseedhar Rayaprolu, Alan Moore, Joseph Che Yen Wang, Boon Chong Goh, Juan R. Perilla, Adam Zlotnick, Suchetana Mukhopadhyay

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16 Scopus citations


In vitro assembly of alphavirus nucleocapsid cores, called core-like particles (CLPs), requires a polyanionic cargo. There are no sequence or structure requirements to encapsidate single-stranded nucleic acid cargo. In this work, we wanted to determine how the length of the cargo impacts the stability and structure of the assembled CLPs. We hypothesized that cargo neutralizes the basic region of the alphavirus capsid protein and if the cargo is long enough, it will also act to scaffold the CP monomers together. Experimentally we found that CLPs encapsidating short 27mer oligonucleotides were less stable than CLPs encapsidating 48mer or 90mer oligonucleotides under different chemical and thermal conditions. Furthermore, cryo-EM studies showed there were structural differences between CLPs assembled with 27mer and 48mer cargo. To mimic the role of the cargo in CLP assembly we made a mutant (4D) where we substituted a cluster of four Lys residues in the CP with four Asp residues. We found that these few amino acid substitutions were enough to initiate CLP assembly in the absence of cargo. The cargo-free 4D CLPs show higher resistance to ionic strength and increased temperature compared to wild-type cargo containing CLPs suggesting their CLP assembly mechanism might also be different.

Original languageEnglish (US)
Article number484003
JournalJournal of Physics Condensed Matter
Issue number48
StatePublished - Nov 10 2017

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Condensed Matter Physics


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