EMD-22332

Single-particle
20.0 Å
EMD-22332 Deposition: 20/07/2020
Map released: 02/09/2020
Last modified: 02/09/2020
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-22332

Phage SPN3US mottled capsid (glutaraldehyde-fixed)

EMD-22332

Single-particle
20.0 Å
EMD-22332 Deposition: 20/07/2020
Map released: 02/09/2020
Last modified: 02/09/2020
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Salmonella phage SPN3US
Sample: Salmonella phage SPN3US

Deposition Authors: Heymann JB, Wang B, Newcomb WW, Wu W, Winkler DC, Cheng N, Reilly ER, Hsia R-C, Thomas JA, Steven AC
The Mottled Capsid of theSalmonellaGiant Phage SPN3US, a Likely Maturation Intermediate with a Novel Internal Shell.
PUBMED: 32825132
DOI: doi:10.3390/v12090910
ISSN: 1999-4915
Abstract:
"Giant" phages have genomes of >200 kbp, confined in correspondingly large capsids whose assembly and maturation are still poorly understood. Nevertheless, the first assembly product is likely to be, as in other tailed phages, a procapsid that subsequently matures and packages the DNA. The associated transformations include the cleavage of many proteins by the phage-encoded protease, as well as the thinning and angularization of the capsid. We exploited an amber mutation in the viral protease gene of the Salmonella giant phage SPN3US, which leads to the accumulation of a population of capsids with distinctive properties. Cryo-electron micrographs reveal patterns of internal density different from those of the DNA-filled heads of virions, leading us to call them "mottled capsids". Reconstructions show an outer shell with T = 27 symmetry, an embellishment of the HK97 prototype composed of the major capsid protein, gp75, which is similar to some other giant viruses. The mottled capsid has a T = 1 inner icosahedral shell that is a complex network of loosely connected densities composed mainly of the ejection proteins gp53 and gp54. Segmentation of this inner shell indicated that a number of densities (~12 per asymmetric unit) adopt a "twisted hook" conformation. Large patches of a proteinaceous tetragonal lattice with a 67 Å repeat were also present in the cell lysate. The unexpected nature of these novel inner shell and lattice structures poses questions as to their functions in virion assembly.