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Three-Dimensional Structure of Victorivirus HvV190S Suggests Coat Proteins in Most Totiviruses Share a Conserved Core

Summary

This research reveals the detailed 3D structure of a fungal virus called HvV190S using advanced microscopy techniques. The study shows that despite differences in protein sequences, many related viruses share a similar structural core in their protective shell. This finding helps us better understand how these viruses are built and function. Impacts on everyday life: – Improves our understanding of plant diseases caused by fungal viruses – Advances methods for studying tiny biological structures – Could help develop ways to control crop diseases – May lead to new antifungal treatments – Contributes to basic knowledge of virus structure and evolution

Background

Double-stranded (dsRNA) fungal viruses are currently assigned to six different families. Those from the family Totiviridae are characterized by nonsegmented genomes and single-layer capsids, 300-450 Å in diameter. Helminthosporium victoriae virus 190S (HvV190S), prototype of recently recognized genus Victorivirus, infects the filamentous fungus Helminthosporium victoriae, which causes Victoria blight of oats.

Objective

To determine and analyze the three-dimensional structures of HvV190S virions and two types of virus-like particles (capsids lacking dsRNA and capsids lacking both dsRNA and RdRp) at subnanometer resolution using cryo-electron microscopy and image reconstruction techniques.

Results

The HvV190S capsid is thin and smooth, containing 120 copies of coat protein arranged in a ‘T=2’ icosahedral lattice characteristic of other dsRNA viruses. Both subunits have a similar fold but differ from ScV-L-A in many details except for a core α-helical region. This core region is predicted to be conserved among many other totiviruses.

Conclusion

The structures of other victoriviruses are predicted to be highly similar to HvV190S and the structures of most if not all totiviruses including Leishmania RNA virus 1 are likely similar as well. The study reveals a conserved structural core in the coat proteins across diverse members of the Totiviridae family despite low sequence similarity.
  • Published in:PLOS Pathogens,
  • Study Type:Structural Biology Study,
  • Source: 10.1371/journal.ppat.1003225
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