Visualization of the herpes simplex virus portal in situ by cryo-electron tomography

Journal Article · Thu May 10 04:00:00 EDT 2007 · Virology

DOI:https://doi.org/10.1016/j.virol.2006.10.047· OSTI ID:20977021

Cardone, Giovanni ^[1]; Winkler, Dennis C ^[1]; Trus, Benes L ^[1]; Cheng, Naiqian ^[1]; Heuser, John E ^[2]; Newcomb, William W ^[3]; Brown, Jay C ^[3]; Steven, Alasdair C ^[1]

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1. Laboratory of Structural Biology Research, National Institute of Arthritis and Musculoskeletal and Skin Diseases, Building 50, Rm 1517, MSC 8025, 50 South Drive, National Institutes of Health, Bethesda, MD 20892-8025 (United States)
2. Department of Cell Biology, Washington University School of Medicine, St. Louis, MO 63110 (United States)
3. Department of Microbiology and Cancer Center, University of Virginia Health System, Charlottesville, VA 22908 (United States)

Herpes simplex virus type 1 (HSV-1), the prototypical herpesvirus, has an icosahedral nucleocapsid surrounded by a proteinaceous tegument and a lipoprotein envelope. As in tailed bacteriophages, the icosahedral symmetry of the capsid is broken at one of the 12 vertices, which is occupied by a dodecameric ring of portal protein, UL6, instead of a pentamer of the capsid protein, UL19. The portal ring serves as a conduit for DNA entering and exiting the capsid. From a cryo-EM reconstruction of capsids immuno-gold-labeled with anti-UL6 antibodies, we confirmed that UL6 resides at a vertex. To visualize the portal in the context of the assembled capsid, we used cryo-electron tomography to determine the three-dimensional structures of individual A-capsids (empty, mature capsids). The similarity in size and overall shape of the portal and a UL19 pentamer - both are cylinders of {approx} 800 kDa - combined with residual noise in the tomograms, prevented us from identifying the portal vertices directly; however, this was accomplished by a computational classification procedure. Averaging the portal-containing subtomograms produced a structure that tallies with the isolated portal, as previously reconstructed by cryo-EM. The portal is mounted on the outer surface of the capsid floor layer, with its narrow end pointing outwards. This disposition differs from that of known phage portals in that the bulk of its mass lies outside, not inside, the floor. This distinction may be indicative of divergence at the level of portal-related functions other than its role as a DNA channel.

• OSTI ID: 20977021
• Journal Information: Virology, Journal Name: Virology Journal Issue: 2 Vol. 361; ISSN VIRLAX; ISSN 0042-6822
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
ANTIBODIES
BACTERIOPHAGES
DNA
ELECTRON MICROSCOPY
HERPES SIMPLEX
LIPOPROTEINS
TOMOGRAPHY