This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Kim, S. K.
Right arrow Articles by O'Callaghan, D. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Kim, S. K.
Right arrow Articles by O'Callaghan, D. J.

 Previous Article  |  Next Article 

Journal of Virology, May 2006, p. 5041-5049, Vol. 80, No. 10
0022-538X/06/$08.00+0     doi:10.1128/JVI.80.10.5041-5049.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

The Unique IR2 Protein of Equine Herpesvirus 1 Negatively Regulates Viral Gene Expression

Seong K. Kim, Byung C. Ahn, Randy A. Albrecht,{dagger} and Dennis J. O'Callaghan*

Department of Microbiology and Immunology, and Center for Molecular and Tumor Virology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130-3932

Received 21 December 2005/ Accepted 20 February 2006

The IR2 protein (IR2P) is a truncated form of the immediate-early protein (IEP) lacking the essential acidic transcriptional activation domain (TAD) and serine-rich tract and yet retaining binding domains for DNA and TFIIB and nuclear localization signal (NLS). Analysis of the IR2 promoter indicated that the IR2 promoter was upregulated by the EICP0P. The IR2P was first detected in the nucleus at 5 h postinfection in equine herpesvirus 1 (EHV-1)-infected HeLa and equine NBL6 cells. Transient-transfection assays revealed that (i) the IR2P by itself downregulated EHV-1 early promoters (EICP0, TK, EICP22, and EICP27) in a dose-dependent manner; (ii) the IR2P abrogated the IEP and the EICP27P (UL5) mediated transactivation of viral promoters in a dose-dependent manner; and (iii) the IR2P, like the IEP itself, also downregulated the IE promoter, indicating that the IEP TAD is not necessary to downregulate the IE promoter. In vitro interaction assays revealed that the IR2P interacts with TATA box-binding protein (TBP). The essential domain(s) of the IR2P that mediate negative regulation were mapped to amino acid residues 1 to 706, indicating that the DNA-binding domain and the NLS of the IR2P may be important for the downregulation. In transient-transfection and virus growth assays, the IR2P reduced EHV-1 production by 23-fold compared to virus titers achieved in cells transfected with the empty vector. Overall, these studies suggest that the IR2P downregulates viral gene expression by acting as a dominant-negative protein that blocks IEP-binding to viral promoters and/or squelching the limited supplies of TFIIB and TBP.

* Corresponding author. Mailing address: Department of Microbiology and Immunology, Louisiana State University Health Sciences Center, 1501 Kings Highway, P.O. Box 33932, Shreveport, LA 71130-3932. Phone: (318) 675-5750. Fax: (318) 675-5764. E-mail: docall{at}lsuhsc.edu.

{dagger} Present address: Department of Microbiology, Box 1124, Mount Sinai School of Medicine, New York, NY 10029.

Journal of Virology, May 2006, p. 5041-5049, Vol. 80, No. 10
0022-538X/06/$08.00+0     doi:10.1128/JVI.80.10.5041-5049.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.





Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»