title: Identification of functional domains of the IR2 protein of equine herpesvirus 1 required for inhibition of viral gene expression and replication.
abstract: The equine herpesvirus 1 (EHV-1) negative regulatory IR2 protein (IR2P), an early 1,165-amino acid (aa) truncated form of the 1487-aa immediate-early protein (IEP), lacks the trans-activation domain essential for IEP activation functions but retains domains for binding DNA, TFIIB, and TBP and the nuclear localization signal. IR2P mutants of the N-terminal region which lack either DNA-binding activity or TFIIB-binding activity were unable to down-regulate EHV-1 promoters. In EHV-1-infected cells expressing full-length IR2P, transcription and protein expression of viral regulatory IE, early EICP0, IR4, and UL5, and late ETIF genes were dramatically inhibited. Viral DNA levels were reduced to 2.1% of control infected cells, but were vey weakly affected in cells that express the N-terminal 706 residues of IR2P. These results suggest that IR2P function requires the two N-terminal domains for binding DNA and TFIIB as well as the C-terminal residues 707 to 1116 containing the TBP-binding domain.
authors.affiliation: Department of Microbiology and Immunology, and Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana LA 71130-3932, USA. skim1@lsuhsc.edu
authors.forename: Seong K
authors.initials: SK
authors.lastname: Kim
authors.forename: Seongman
authors.initials: S
authors.lastname: Kim
authors.forename: Gan
authors.initials: G
authors.lastname: Dai
authors.forename: Yunfei
authors.initials: Y
authors.lastname: Zhang
authors.forename: Byung C
authors.initials: BC
authors.lastname: Ahn
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: O'Callaghan
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015967:Gene Expression Regulation, Viral; D004861:Herpesvirus 1, Equid / Q000235:genetics / Q000502:physiology*; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D017434:Protein Structure, Tertiary; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D004268:DNA-Binding Proteins; D050505:Mutant Proteins; D014764:Viral Proteins