Upstream stimulatory factor family binds to the herpes simplex virus type 1 latency-associated transcript promoter

The herpes simplex Virus type 1 (HSV-1) latency-associated transcript (LAT) promoter 1 (LPI) is the only viral promoter that exhibits detectable transcriptional activity during a latent HSV infection. The LAT promoter-binding factor (LPBF) regulatory sequence (nucleotides -65 to -72 relative to the transcriptional stat? site of the 8.3-kb primary transcript) closely resembles the core recognition sequence required for binding members of the upstream stimulatory factor (USF)/major late transcription factor (MLTF) family, In this analysis, we demonstrate that oligonucleotides containing either the LPBF recognition sequence or the USF/MLTF recognition sequences from previously described promoters bind cellular factors which exhibit very similar mobilities in electrophoretic mobility shift (EMS) analyses. We also observe a high degree of similarity in competition profiles obtained in competition EMS analyses utilizing oligonucleotides containing recognition sequences for either LPBF or USF/MLTF. Furthermore, antibody supershift EMS analyses have demonstrated that the factors binding the LPBF or USF/MLTF recognition sites in these oligonucleotides are antigenically related, if not identical, and that greater than 90% of the LPBF-binding activity is antigenically related to USF. In addition, we demonstrate that both forms of in vitro-translated USF proteins (43 and 44 kDa) bind to the LPBF recognition sequence within HSV-1 LPI. Taken together, these data indicate that USF is capable of binding to the HSV-I LPBF recognition sequence and that USF is a major LPBF-binding activity in cells of neuronal and nonneuronal lineage. These data further support the hypothesis that USF may indeed play a significant role in the transcriptional activity of HSV-I LPI. (C) 1997 Academic Press.