title: Characterization of cis-acting elements required for autorepression of the equine herpesvirus 1 IE gene.
abstract: The immediate-early protein (IEP), the major regulatory protein encoded by the IE gene of equine herpesvirus 1 (EHV-1), plays a crucial role as both transcription activator and repressor during a productive lytic infection. To investigate the mechanism by which the EHV-1 IEP inhibits its own promoter, IE promoter-luciferase reporter plasmids containing wild-type and mutant IEP-binding site (IEBS) were constructed and used for luciferase reporter assays. The IEP inhibited transcription from its own promoter in the presence of a consensus IEBS (5'-ATCGT-3') located near the transcription initiation site but did not inhibit when the consensus sequence was deleted. To determine whether the distance between the TATA box and the IEBS affects transcriptional repression, the IEBS was displaced from the original site by the insertion of synthetic DNA sequences. Luciferase reporter assays revealed that the IEP is able to repress its own promoter when the IEBS is located within 26-bp from the TATA box. We also found that the proper orientation and position of the IEBS were required for the repression by the IEP. Interestingly, the level of repression was significantly reduced when a consensus TATA sequence was deleted from the promoter region, indicating that the IEP efficiently inhibits its own promoter in a TATA box-dependent manner. Taken together, these results suggest that the EHV-1 IEP delicately modulates autoregulation of its gene through the consensus IEBS that is near the transcription initiation site and the TATA box.
authors.affiliation: Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, LA 71130-3932, USA.
authors.forename: Seongman
authors.initials: S
authors.lastname: Kim
authors.forename: Gan
authors.initials: G
authors.lastname: Dai
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: O'Callaghan
authors.forename: Seong Kee
authors.initials: SK
authors.lastname: Kim
mesh_terms: D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D015536:Down-Regulation; D015967:Gene Expression Regulation, Viral; D004861:Herpesvirus 1, Equid / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D006706:Homeostasis; D006734:Horse Diseases / Q000821:virology*; D006736:Horses; D017874:Immediate-Early Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D012045:Regulatory Sequences, Nucleic Acid
chemical_list: D017874:Immediate-Early Proteins