The equine herpesvirus 1 EICP27 protein enhances gene expression via an interaction with TATA box-binding protein.
The mechanism(s) by which the early EICP27 gene product cooperates with other equine herpesvirus 1 (EHV-1) regulatory proteins to achieve maximal promoter activity remains unknown. Transient transfection assays revealed that deletion of residues 93-140 of the 470-aa EICP27 protein substantially diminished its activation of the immediate-early (IE) promoter, whereas deletion of residues 140-470 that contain a zinc-finger motif abolished this activity. Fluorescence microscopy of cells expressing the full-length EICP27 protein or portions of this protein revealed that an arginine-rich sequence spanning residues 178-185 mediates nuclear entry. Experiments employing the mammalian Gal4 two-plasmid system revealed that the EICP27 protein does not possess an independent trans-activation domain (TAD). Protein-protein interaction assays using purified proteins revealed that residues 124-220 of the EICP27 protein mediate its direct interaction with TATA box-binding protein (TBP). Partial deletion of this TBP-binding domain attenuated the ability of the EICP27 protein to stimulate the IE and early EICP0 promoters by 68% and 71%, respectively, indicating the importance of this protein-protein interaction.
Albrecht
Randy A
RA
Center for Molecular and Tumor Virology and Department of Microbiology and Immunology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130-3932, USA.
Kim
Seong K
SK
Zhang
Yunfei
Y
Zhao
Yuhe
Y
O'Callaghan
Dennis J
DJ
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D017353:Gene Deletion; D015967:Gene Expression Regulation, Viral; D004861:Herpesvirus 1, Equid / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000502:physiology; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D035381:TATA-Binding Protein Associated Factors / Q000235:genetics; D035181:TATA-Box Binding Protein / Q000378:metabolism*; D015533:Transcriptional Activation; D054334:Viral Regulatory and Accessory Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D017874:Immediate-Early Proteins; D019913:Nuclear Localization Signals; D035381:TATA-Binding Protein Associated Factors; D035181:TATA-Box Binding Protein; D054334:Viral Regulatory and Accessory Proteins