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Virology. 2017 Oct;510:216-223. doi: 10.1016/j.virol.2017.07.015. Epub 2017 Jul 24.

Cryo-EM maps reveal five-fold channel structures and their modification by gatekeeper mutations in the parvovirus minute virus of mice (MVM) capsid.

Author information

1
Department of Medicine, Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA.
2
Lake Erie College of Osteopathic Medicine, 1858 West Grandview Blvd., Erie, PA 16509, USA.
3
Bizkaia Science and Technology Park, Building 800, Derio, Bizkaia, Spain.
4
Department of Structural Biology, University of Pittsburgh School of Medicine, Biomedical Science Tower 3, Room 2047, 3501 5th Ave, Pittsburgh, PA, USA.
5
Department of Laboratory Medicine, Yale University School of Medicine, 333, Cedar St., New Haven, CT 06520-8035, USA.
6
Department of Laboratory Medicine, Yale University School of Medicine, 333, Cedar St., New Haven, CT 06520-8035, USA; Department of Genetics, Yale University School of Medicine, 333, Cedar St., New Haven, CT 06520-8035, USA.
7
Department of Medicine, Pennsylvania State University College of Medicine, 500 University Drive, Hershey, PA 17033, USA. Electronic address: shafenstein@hmc.psu.edu.

Abstract

In minute virus of mice (MVM) capsids, icosahedral five-fold channels serve as portals mediating genome packaging, genome release, and the phased extrusion of viral peptides. Previous studies suggest that residues L172 and V40 are essential for channel function. The structures of MVMi wildtype, and mutant L172T and V40A virus-like particles (VLPs) were solved from cryo-EM data. Two constriction points, termed the mid-gate and inner-gate, were observed in the channels of wildtype particles, involving residues L172 and V40 respectively. While the mid-gate of V40A VLPs appeared normal, in L172T adjacent channel walls were altered, and in both mutants there was major disruption of the inner-gate, demonstrating that direct L172:V40 bonding is essential for its structural integrity. In wildtype particles, residues from the N-termini of VP2 map into claw-like densities positioned below the channel opening, which become disordered in the mutants, implicating both L172 and V40 in the organization of VP2 N-termini.

KEYWORDS:

Entry/exit portal dynamics; Five-fold channel; Gatekeeper mutation; Low resolution cryo-EM density; MVM, cryo-EM image reconstruction; Minute virus of mice; Mutant capsid; Packaging single-stranded DNA; Parvovirus

PMID:
28750325
PMCID:
PMC5601314
DOI:
10.1016/j.virol.2017.07.015
[Indexed for MEDLINE]
Free PMC Article

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