Transactivation of human immunodeficiency virus type 1 long terminal repeat-directed gene expression by the human foamy virus bel1 protein requires a specific DNA sequence.
Human foamy virus (HFV) encodes the transcriptional transactivator bel1. The bel1 protein transactivates HFV long terminal repeat (LTR)-directed gene expression by recognizing a region in U3. It also transactivates human immunodeficiency virus type 1 (HIV-1) LTR-directed gene expression in transient transfection assays. To identify the specific region in HIV-1 LTR responsible for bel1 action, we examined the effect of bel1 on chloramphenicol acetyltransferase (CAT) gene expression in transfected cells with a series of mutant HIV-1 LTR/CAT plasmids. The region between -158 and -118 from the transcription initiation site, immediately upstream of the core enhancer element, was identified as responsible for the transactivation by bel1. In addition, bel1 transactivated a heterologous promoter when this region was positioned upstream of it in the sense and antisense orientations. Optimal transactivation of the HIV-1 LTR by bel1 did not require an intact TAR sequence, suggesting that the binding of tat to the TAR sequence is not a prerequisite for bel1 function in HIV-1 LTR-directed gene expression. In the region of the HIV-1 LTR that is necessary for the bel1-mediated transactivation, we have found a sequence which is conserved between HIV-1 and HFV. Our results suggest that the bel1 action on HIV-1 seems to be mediated by a specific DNA sequence which is shared by both the HIV-1 LTR and HFV LTR.
Lee
A H
AH
Department of Life Science, Pohang Institute of Science and Technology, Republic of Korea.
Lee
K J
KJ
Kim
S
S
Sung
Y C
YC
D001483:Base Sequence; D015500:Chloramphenicol O-Acetyltransferase; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000494:pharmacology*; D016325:HIV Long Terminal Repeat / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D012191:Retroviridae Proteins / Q000494:pharmacology*; D018139:Simplexvirus / Q000235:genetics; D016092:Spumavirus / Q000235:genetics*; D015534:Trans-Activators; D015533:Transcriptional Activation / Q000187:drug effects*; D014764:Viral Proteins / Q000494:pharmacology*
D004268:DNA-Binding Proteins; D012191:Retroviridae Proteins; D015534:Trans-Activators; D014764:Viral Proteins; C074061:bel1 protein, Human foamy virus; D015500:Chloramphenicol O-Acetyltransferase