Scientific Reports (Jul 2017)

Coronavirus nucleocapsid proteins assemble constitutively in high molecular oligomers

  • Yingying Cong,
  • Franziska Kriegenburg,
  • Cornelis A. M. de Haan,
  • Fulvio Reggiori

DOI
https://doi.org/10.1038/s41598-017-06062-w
Journal volume & issue
Vol. 7, no. 1
pp. 1 – 10

Abstract

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Abstract Coronaviruses (CoV) are enveloped viruses and rely on their nucleocapsid N protein to incorporate the positive-stranded genomic RNA into the virions. CoV N proteins form oligomers but the mechanism and relevance underlying their multimerization remain to be fully understood. Using in vitro pull-down experiments and density glycerol gradients, we found that at least 3 regions distributed over its entire length mediate the self-interaction of mouse hepatitis virus (MHV) and severe acute respiratory syndrome coronavirus (SARS-CoV) N protein. The fact that these regions can bind reciprocally between themselves provides a possible molecular basis for N protein oligomerization. Interestingly, cytoplasmic N molecules of MHV-infected cells constitutively assemble into oligomers through a process that does not require binding to genomic RNA. Based on our data, we propose a model where constitutive N protein oligomerization allows the optimal loading of the genomic viral RNA into a ribonucleoprotein complex via the presentation of multiple viral RNA binding motifs.