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Updated: Feb 9, 2026

Generation and Assembly of Virus-Specific Nucleocapsids of the Respiratory Syncytial Virus
Published on: July 27, 2021
The nucleocapsid protein of coronavirus infectious bronchitis virus: crystal structure of its N-terminal domain and
Hui Fan1, Amy Ooi, Yong Wah Tan
1School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551.
Abstract:
The coronavirus nucleocapsid (N) protein packages viral genomic RNA into a ribonucleoprotein complex. Interactions between N proteins and RNA are thus crucial for the assembly of infectious virus particles. The 45 kDa recombinant nucleocapsid N protein of coronavirus infectious bronchitis virus (IBV) is highly sensitive to proteolysis. We obtained a stable fragment of 14.7 kDa spanning its N-terminal residues 29-160 (IBV-N29-160). Like the N-terminal RNA binding domain (SARS-N45-181) of the severe acute respiratory syndrome virus (SARS-CoV) N protein, the crystal structure of the IBV-N29-160 fragment at 1.85 A resolution reveals a protein core composed of a five-stranded antiparallel beta sheet with a positively charged beta hairpin extension and a hydrophobic platform that are probably involved in RNA binding. Crosslinking studies demonstrate the formation of dimers, tetramers, and higher multimers of IBV-N. A model for coronavirus shell formation is proposed in which dimerization of the C-terminal domain of IBV-N leads to oligomerization of the IBV-nucleocapsid protein and viral RNA condensation.
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