The product of ORF O located within the domain of herpes simplex virus 1 genome transcribed during latent infection binds to and inhibits in vitro binding of infected cell protein 4 to its cognate DNA site.
The partially overlapping ORF P and ORF O are located within the domains of the herpes simplex virus 1 genome transcribed during latency. Earlier studies have shown that ORF P is repressed by infected cell protein 4 (ICP4), the major viral regulatory protein, binding to its cognate site at the transcription initiation site of ORF P. The ORF P protein binds to p32, a component of the ASF/SF2 alternate splicing factors; in cells infected with a recombinant virus in which ORF P was derepressed there was a significant decrease in the expression of products of key regulatory genes containing introns. We report that (i) the expression of ORF O is repressed during productive infection by the same mechanism as that determining the expression of ORF P; (ii) in cells infected at the nonpermissive temperature for ICP4, ORF O protein is made in significantly lower amounts than the ORF P protein; (iii) the results of insertion of a sequence encoding 20 amino acids between the putative initiator methionine codons of ORF O and ORF P suggest that ORF O initiates at the methionine codon of ORF P and that the synthesis of ORF O results from frameshift or editing of its RNA; and (iv) glutathione S-transferase-ORF O fusion protein bound specifically ICP4 and precluded its binding to its cognate site on DNA in vitro. These and earlier results indicate that ORF P and ORF O together have the capacity to reduce the synthesis or block the expression of regulatory proteins essential for viral replication in productive infection.
Randall
G
G
The Marjorie B. Kovler Viral Oncology Laboratories, University of Chicago, 910 East 58th Street, Chicago IL 60637, USA.
Lagunoff
M
M
Roizman
B
B
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004247:DNA; D004268:DNA-Binding Proteins / Q000378:metabolism*; D016679:Genome, Viral; D018259:Herpesvirus 1, Human / Q000235:genetics* / Q000502:physiology; D017874:Immediate-Early Proteins / Q000378:metabolism*; D008715:Methionine / Q000378:metabolism; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011817:Rabbits; D017735:Virus Latency / Q000235:genetics*
D004268:DNA-Binding Proteins; D017874:Immediate-Early Proteins; C048925:herpes simplex virus, type 1 protein ICP4; D004247:DNA; D008715:Methionine