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Updated: May 23, 2026

Generation and Assembly of Virus-Specific Nucleocapsids of the Respiratory Syncytial Virus
Published on: July 27, 2021
Capsid structure and its stability at the late stages of bacteriophage SPP1 assembly
Helen E White1, Michael B Sherman, Sandrine Brasilès
1Crystallography, Institute for Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, University of London, London, United Kingdom.
Abstract:
The structure of the bacteriophage SPP1 capsid was determined at subnanometer resolution by cryo-electron microscopy and single-particle analysis. The icosahedral capsid is composed of the major capsid protein gp13 and the auxiliary protein gp12, which are organized in a T=7 lattice. DNA is arranged in layers with a distance of ~24.5 Å. gp12 forms spikes that are anchored at the center of gp13 hexamers. In a gp12-deficient mutant, the centers of hexamers are closed by loops of gp13 coming together to protect the SPP1 genome from the outside environment. The HK97-like fold was used to build a pseudoatomic model of gp13. Its structural organization remains unchanged upon tail binding and following DNA release. gp13 exhibits enhanced thermostability in the DNA-filled capsid. A remarkable convergence between the thermostability of the capsid and those of the other virion components was found, revealing that the overall architecture of the SPP1 infectious particle coevolved toward high robustness.
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