A novel latency-active promoter is contained within the herpes simplex virus type 1 UL flanking repeats.
Herpes simplex virus type 1 (HSV-1) expresses a unique series of RNA molecules, the latency-associated transcripts or LATs, during latent infection of neuronal tissues. Previous studies by others have described a TATA box-containing latency-active promoter, referred to here as LAP1, located approximately 700 bp upstream of the 5' end of the major 2.0-kb LAT. In this report, transient gene expression assays were employed to identify a second, novel latency-active promoter (LAP2) present within a region downstream of LAP1 and 5' proximal to the major 2.0-kb LAT. In contrast to LAP1, this promoter lacks a TATA box but possesses cis-acting regulatory elements and other features frequently observed within eukaryotic housekeeping gene promoters. Unlike most other HSV promoters, LAP2 was down-regulated by the viral transcriptional activators ICP4 and ICP0. The majority of LAP2-positive regulatory elements were located within sequences from -257 to -58 relative to the 5' end of the 2.0-kb LAT, and the basal promoter mapped within sequences from -14 to +28. RNase protection experiments demonstrated that chimeric LAT-chloramphenicol acetyltransferase transcripts produced in the transient assays initiated at or near the 5' end of the major 2-kb LAT. Tn5 insertional mutagenesis of the ICP4 regulatory gene determined that down-regulation of LAP2 required the ICP4 transactivating domain and targeted the minimal promoter region as the site of action by ICP4. Replicating recombinant viruses containing a LAP2-lacZ reporter gene cassette in an ectopic site (glycoprotein C locus) were shown to be active in mouse trigeminal ganglia. Taken together, these experiments suggest that the LAT region of the HSV-1 genome contains at least two latency-active promoters which may play different roles in expressing the various LATs. Alternatively, these promoters may comprise a larger promoter-regulatory complex which may influence transcription during latency.
Goins
W F
WF
Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pennsylvania 15261.
Sternberg
L R
LR
Croen
K D
KD
Krause
P R
PR
Hendricks
R L
RL
Fink
D J
DJ
Straus
S E
SE
Levine
M
M
Glorioso
J C
JC
D000818:Animals; D001483:Base Sequence; D004252:DNA Mutational Analysis; D015536:Down-Regulation; D005260:Female; D015967:Gene Expression Regulation, Viral / Q000187:drug effects; D018259:Herpesvirus 1, Human / Q000235:genetics*; D017874:Immediate-Early Proteins / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D017384:Sequence Deletion; D014162:Transfection; D012668:Trigeminal Ganglion / Q000382:microbiology; D044767:Ubiquitin-Protein Ligases; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000235:genetics; D014764:Viral Proteins / Q000494:pharmacology; D017735:Virus Latency / Q000235:genetics*
D017874:Immediate-Early Proteins; D012333:RNA, Messenger; D014759:Viral Envelope Proteins; D014764:Viral Proteins; C038535:glycoprotein gC, herpes simplex virus type 1; C048925:herpes simplex virus, type 1 protein ICP4; D044767:Ubiquitin-Protein Ligases; C051804:Vmw110 protein, Human herpesvirus 1