Primate cytomegalovirus assembly: evidence that DNA packaging occurs subsequent to B capsid assembly.
Results presented here show that when cytomegalovirus (strain Colburn)-infected cells are treated with the DNA synthesis inhibitor hydroxyurea or phosphonoformate, one type of intranuclear capsid accumulates. These particles appeared to contain symmetrically organized internal material, and had a protein composition and sedimentation rate characteristic of B capsids. Radiolabeling experiments provided evidence that a population of B capsids lacking DNA is present during the course of a normal infection. These capsids sedimented slightly slower than the peak of viral DNA in the same region of the gradient, and had a ratio of DNA/protein that was estimated to be sevenfold lower than that of the faster sedimenting C capsids. DNA in both the B and C capsid regions of such gradients was found to be relatively resistant to digestion with DNase. The possibility is considered that herpesvirus B capsids lacking DNA may be counterparts of unexpanded proheads in the bacteriophage assembly pathway.
Lee
J Y
JY
Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Irmiere
A
A
Gibson
W
W
D002213:Capsid / Q000032:analysis / Q000096:biosynthesis*; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D003587:Cytomegalovirus / Q000235:genetics* / Q000502:physiology / Q000648:ultrastructure; D004279:DNA, Viral / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005347:Fibroblasts; D017245:Foscarnet; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D008854:Microscopy, Electron; D010746:Phosphonoacetic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D014771:Virion / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure
D004279:DNA, Viral; D017245:Foscarnet; D010746:Phosphonoacetic Acid; D006918:Hydroxyurea