Identification of cellular proteins that bind to the human immunodeficiency virus type 1 trans-activation-responsive TAR element RNA.
Human immunodeficiency virus type 1 (HIV-1) trans-activator protein Tat activates the expression of its viral long terminal repeat (LTR) through a target transactivation-responsive element termed TAR. We have constructed cell lines that constitutively express the HIV-1 Tat protein. Analyses of nuclear proteins from these cells and from matched control cells that do not express Tat have identified three proteins that bind to a radiolabeled HIV-1 TAR RNA probe. These polypeptides are 100 kDa, 62 kDa, and 46 kDa in size. Competition experiments using a wild-type TAR RNA sequence, a biologically inactive mutant sequence of TAR, and an unrelated RNA species demonstrated that these proteins show higher binding affinity to wild-type TAR than to the other two non-trans-activatable sequences. We hypothesize that these cellular proteins may mediate a function necessary in Tat-dependent activation of the LTR. The fact that no differences were seen in the binding profiles of nuclear proteins to TAR RNA in Tat-producing and Tat-nonproducing cells suggests that Tat does not directly interact with TAR.
Gatignol
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Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892.
Kumar
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Rabson
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Jeang
K T
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D001483:Base Sequence; D002352:Carrier Proteins / Q000302:isolation & purification; D005814:Genes, Viral; D015756:Genes, tat; D015497:HIV-1 / Q000235:genetics*; D006367:HeLa Cells / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D015347:RNA Probes; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification; D012367:RNA, Viral / Q000235:genetics*; D016601:RNA-Binding Proteins; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
D002352:Carrier Proteins; D015347:RNA Probes; D012333:RNA, Messenger; D012367:RNA, Viral; D016601:RNA-Binding Proteins