TAR RNA binding properties and relative transactivation activities of human immunodeficiency virus type 1 and 2 Tat proteins.
Using gel shift assays, we found that the human immunodeficiency virus type 1 (HIV-1) Tat protein (Tat-1) bound both HIV-1 and HIV-2 TAR RNAs with similar high affinities. In contrast, the HIV-2 Tat protein (Tat-2) bound only TAR-2 RNA with high affinity. We conclude that the weak in vivo activity of Tat-2 on the HIV-1 long terminal repeat that has been observed previously is likely the result of low affinity for TAR-1 RNA. Additionally, TAR-2 RNA was found to contain multiple specific binding sites for Tat proteins. GAL4-Tat fusion proteins were analyzed to compare the relative transactivation activities of Tat-1 and Tat-2 in the absence of requirements for binding to TAR RNAs. The GAL4-Tat-2 protein was found to transactivate synthetic promoters containing GAL4 binding sites at levels severalfold higher than did the GAL4-Tat-1 protein.
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Division of Molecular Virology, Baylor College of Medicine, Houston, Texas 77030-3498.
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D000595:Amino Acid Sequence; D001667:Binding, Competitive; D004252:DNA Mutational Analysis; D015967:Gene Expression Regulation, Viral; D015696:Gene Products, tat / Q000378:metabolism*; D006678:HIV / Q000235:genetics*; D015497:HIV-1 / Q000235:genetics; D015498:HIV-2 / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D012367:RNA, Viral / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D015533:Transcriptional Activation; D054322:tat Gene Products, Human Immunodeficiency Virus
D015696:Gene Products, tat; D012367:RNA, Viral; D011993:Recombinant Fusion Proteins; D054322:tat Gene Products, Human Immunodeficiency Virus