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Biochem Biophys Res Commun. 1998 Mar 17;244(2):384-9.

Interaction of the second coding exon of Tat with human EF-1 delta delineates a mechanism for HIV-1-mediated shut-off of host mRNA translation.

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Molecular Virology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0460, USA.


HIV-1 Tat has pleiotropic functions. While its most studied role is to activate transcription from the retroviral long terminal repeat (LTR)-promoter, Tat also has functions as a secretable growth factor, a T-cell activator, and an inducer of cellular apoptosis, amongst others. For its transcriptional function, the first coding exon of Tat appears wholly sufficient; however, lentiviruses (HIVs and SIVs) maintain and conserve a second coding exon for Tat. While the function(s) of the second exon of Tat has remained largely unknown, its integrity in lentiviral genomes suggests biological importance, possibly a role in non-transcriptional activities. To understand better the biology of the second exon of Tat in HIV-1 infection of cells, we have searched for cellular proteins that bind specifically to this protein domain. Here, we report that the human translation elongation factor 1-delta (EF-1 delta) binds to the second exon of HIV-1 Tat. Interaction between Tat and EF-1 delta dramatically reduces the efficiency of the translation of cellular, but not viral, mRNAs. These findings suggest that a non-transcriptional activity of Tat modulates cellular protein synthesis, thereby affecting the metabolism of host cells.

[Indexed for MEDLINE]

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