The gamma2 late glycoprotein K promoter of equine herpesvirus 1 is differentially regulated by the IE and EICP0 proteins.
The equine herpesvirus 1 immediate-early (IE) phosphoprotein is essential for the activation of transcription from viral early and late promoters and trans-represses its own promoter. Transient-transfection assays showed that the IE protein trans-represses the gamma2 late gK promoter. Gel shift and DNase I footprinting assays demonstrated that the IE protein binds to the gK promoter sequences from -42 to -26 and from -13 to +12 that overlap the transcription initiation site (+1). These results indicated that the IE protein binds to the transcription initiation site of the gK promoter sequences, thereby repressing transcription. On the other hand, the EICP0 protein trans-activates the gamma2 late gK promoter [Bowles, D. E., Holden, V. R., Zhao, Y., and O'Callaghan, D. J. (1997). The ICP0 protein of equine herpesvirus 1 is an early protein that independently transactivates expression of all classes of viral promoters. J. Virol. 71, 4904-4914]. Overall, the EICP0 protein is able to release the gK promoter from the repressive effects of the IE protein. It has not been previously demonstrated that the major immediate-early transcriptional regulator of a herpesvirus represses expression of a late gene during infection.
Kim
S K
SK
Department of Microbiology and Immunology, Louisiana State University Medical Center, Shreveport, Louisiana, 71130-3932, USA.
Bowles
D E
DE
O'callaghan
D J
DJ
D000818:Animals; D001665:Binding Sites; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D018397:Equidae; D015967:Gene Expression Regulation, Viral; D004861:Herpesvirus 1, Equid / Q000235:genetics*; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism*
D017874:Immediate-Early Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D014764:Viral Proteins; C095533:gene 63 protein, Equine herpesvirus 1; C076117:UL4 protein, Equine herpesvirus 1; D015500:Chloramphenicol O-Acetyltransferase