Synthetic HIV-1 Tat can dissociate HeLa nuclear protein-TAR RNA complexes in vitro: a novel Tat-nuclear protein interaction.
Multiple binding of Tat and nuclear protein(s) to HIV-1 TAR RNA appears to be essential for the Tat-mediated trans-activation. As synthetic Tat-(1-47), which lacks the basic domain and does not bind TAR RNA in vitro, efficiently transactivated HIV-1 LTR in HeLa nuclear extracts, we hypothesized that Tat might trans-activate by interaction with TAR RNA via a host nuclear protein. The role of nuclear proteins in Tat-TAR interaction was examined through evaluation of several synthetic Tat peptides for ability to bind TAR RNA in vitro both in the presence and in the absence of HeLa nuclear proteins. Our data show that both Tat-(1-47) and Tat-(1-86) interact with TAR RNA-bound nuclear proteins, leading to dissociation of the nuclear protein-TAR RNA complexes; the N-terminal sequence of Tat appears to be involved in this interaction. Thus, after binding to TAR RNA, Tat can interact with a proximal TAR-bound nuclear protein and the resulting Tat-nuclear protein complex, now displaced from TAR, may initiate a facile and rapid assembly of the RNA polymerase II transcription complex. This study thus recognizes a novel interaction between Tat and a nuclear protein(s). Here we propose that the interaction of Tat with a nuclear protein(s) occurring on TAR RNA may be one of several steps in the mechanism of Tat-mediated trans-activation of the HIV-1 LTR.
Wistar Institute, Philadelphia, Pennsylvania 19104.
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Jeyapaul
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Seshamma
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Khan
D001483:Base Sequence; D015696:Gene Products, tat / Q000378:metabolism*; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides; D015347:RNA Probes; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D054322:tat Gene Products, Human Immunodeficiency Virus
D015696:Gene Products, tat; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D015347:RNA Probes; D012367:RNA, Viral; D054322:tat Gene Products, Human Immunodeficiency Virus