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Proc Natl Acad Sci U S A. 2015 Feb 24;112(8):2449-54. doi: 10.1073/pnas.1425008112. Epub 2015 Feb 9.

Lemon-shaped halo archaeal virus His1 with uniform tail but variable capsid structure.

Author information

1
Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030; National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030; and.
2
Department of Biosciences and Institute of Biotechnology, University of Helsinki, FIN-00014 Helsinki, Finland.
3
National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030; and.
4
Department of Biosciences and Institute of Biotechnology, University of Helsinki, FIN-00014 Helsinki, Finland wah@bcm.edu dennis.bamford@helsinki.fi.
5
Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030; National Center for Macromolecular Imaging, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030; and wah@bcm.edu dennis.bamford@helsinki.fi.

Abstract

Lemon-shaped viruses are common in nature but so far have been observed to infect only archaea. Due to their unusual shape, the structures of these viruses are challenging to study and therefore poorly characterized. Here, we have studied haloarchaeal virus His1 using cryo-electron tomography as well as biochemical dissociation. The virions have different sizes, but prove to be extremely stable under various biochemical treatments. Subtomogram averaging of the computationally extracted virions resolved a tail-like structure with a central tail hub density and six tail spikes. Inside the tail there are two cavities and a plug density that separates the tail hub from the interior genome. His1 most likely uses the tail spikes to anchor to host cells and the tail hub to eject the genome, analogous to classic tailed bacteriophages. Upon biochemical treatment that releases the genome, the lemon-shaped virion transforms into an empty tube. Such a dramatic transformation demonstrates that the capsid proteins are capable of undergoing substantial quaternary structural changes, which may occur at different stages of the virus life cycle.

KEYWORDS:

cryo-ET; dissociation; lemon-shaped virus; subtomogram averaging; virus tail organization

PMID:
25675521
PMCID:
PMC4345568
DOI:
10.1073/pnas.1425008112
[Indexed for MEDLINE]
Free PMC Article

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