The novel coactivator C1 (HCF) coordinates multiprotein enhancer formation and mediates transcription activation by GABP.
Transcription of the herpes simplex virus 1 (HSV-1) immediate early (IE) genes is determined by multiprotein enhancer complexes. The core enhancer assembly requires the interactions of the POU-homeodomain protein Oct-1, the viral transactivator alphaTIF and the cellular factor C1 (HCF). In this context, the C1 factor interacts with each protein to assemble the stable enhancer complex. In addition, the IE enhancer cores contain adjacent binding sites for other cellular transcription factors such as Sp1 and GA-binding protein (GABP). In this study, a direct interaction of the C1 factor with GABP is demonstrated, defining the C1 factor as the critical coordinator of the enhancer complex assembly. In addition, mutations that reduce the GABP transactivation potential also impair the C1-GABP interaction, indicating that the C1 factor functions as a novel coactivator of GABP-mediated transcription. The interaction and coordinated assembly of the enhancer proteins by the C1 factor may be critical for the regulation of the HSV lytic-latent cycle.
Vogel
J L
JL
Laboratory of Viral Diseases, National Institutes of Health, Building 4, Room 133, 4 Center Drive, Bethesda, MD 20892, USA.
Kristie
T M
TM
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D051268:GA-Binding Protein Transcription Factor; D017781:Genes, Immediate-Early; D006367:HeLa Cells; D018259:Herpesvirus 1, Human / Q000235:genetics* / Q000502:physiology; D051863:Host Cell Factor C1; D006801:Humans; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000235:genetics* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D015533:Transcriptional Activation; D020798:Two-Hybrid System Techniques
D017931:DNA Primers; D004268:DNA-Binding Proteins; D051268:GA-Binding Protein Transcription Factor; C497692:HCFC1 protein, human; D051863:Host Cell Factor C1; D011506:Proteins; D014157:Transcription Factors