Virion morphology and on-virus spike protein structures of diverse SARS-CoV-2 variants.
Ke, Z., Peacock, T.P., Brown, J.C., Sheppard, C.M., Croll, T.I., Kotecha, A., Goldhill, D.H., Barclay, W.S., Briggs, J.A.G.(2024) EMBO J 
- PubMed: 39543395 
- DOI: https://doi.org/10.1038/s44318-024-00303-1
- Primary Citation of Related Structures:  
9CRC, 9CRD, 9CRE, 9CRF, 9CRG, 9CRH, 9CRI - PubMed Abstract: 
The evolution of SARS-CoV-2 variants with increased fitness has been accompanied by structural changes in the spike (S) proteins, which are the major target for the adaptive immune response. Single-particle cryo-EM analysis of soluble S protein from SARS-CoV-2 variants has revealed this structural adaptation at high resolution. The analysis of S trimers in situ on intact virions has the potential to provide more functionally relevant insights into S structure and virion morphology. Here, we characterized B.1, Alpha, Beta, Gamma, Delta, Kappa, and Mu variants by cryo-electron microscopy and tomography, assessing S cleavage, virion morphology, S incorporation, "in-situ" high-resolution S structures, and the range of S conformational states. We found no evidence for adaptive changes in virion morphology, but describe multiple different positions in the S protein where amino acid changes alter local protein structure. Taken together, our data are consistent with a model where amino acid changes at multiple positions from the top to the base of the spike cause structural changes that can modulate the conformational dynamics of the S protein.
Organizational Affiliation: 
Department of Cell and Virus Structure, Max Planck Institute of Biochemistry, Martinsried, Germany.