Polarized DNA ejection from the herpesvirus capsid.
Ejection of DNA from the capsid is an early step in infection by all herpesviruses. Ejection or DNA uncoating occurs after a parental capsid has entered the host cell cytoplasm, migrated to the nucleus, and bound to a nuclear pore. DNA exits the capsid through the portal vertex and proceeds by way of the nuclear pore complex into the nucleoplasm where it is transcribed and replicated. Here, we describe use of an in vitro uncoating system to determine which genome end exits first from the herpes simplex virus 1 capsid. Purified DNA-containing capsids were bound to a solid surface and warmed under conditions in which some, but not all, of the DNA was ejected. Restriction endonuclease digestion was then used to identify the genomic origin of the ejected DNA. The results support the view that the S segment end exits the capsid first. Preferential release at the S end demonstrates that herpesvirus DNA uncoating conforms to the paradigm in double-stranded DNA bacteriophage where the last end packaged is the first to be ejected. Release of herpes simplex virus 1 DNA beginning at the S end causes the first gene to enter the host cell nucleus to be alpha4, a transcription factor required for expression of early genes.
Newcomb
William W
WW
Department of Microbiology and Cancer Center, Box 800734, University of Virginia Health System, 1300 Jefferson Park Avenue, Charlottesville, VA 22908, USA.
Cockrell
Shelley K
SK
Homa
Fred L
FL
Brown
Jay C
JC
D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002213:Capsid / Q000378:metabolism*; D004261:DNA Replication / Q000502:physiology; D004279:DNA, Viral / Q000187:drug effects / Q000378:metabolism*; D004720:Endonucleases / Q000378:metabolism; D005557:Formaldehyde / Q000494:pharmacology; D016679:Genome, Viral / Q000187:drug effects / Q000502:physiology; D018259:Herpesvirus 1, Human / Q000187:drug effects / Q000378:metabolism*
D004279:DNA, Viral; D005557:Formaldehyde; D004720:Endonucleases