Novel mechanism and factor for regulation by HIV-1 Tat.
Tat regulation of human immunodeficiency virus (HIV) transcription is unique because of its specificity for an RNA target, TAR, and its ability to increase the efficiency of elongation by polymerase. A reconstituted reaction that is Tat-specific and TAR-dependent for activation of HIV transcription has been used to identify and partially purify a cellular activity that is required for trans-activation by Tat, but not by other activators. In the reaction, Tat stimulates the efficiency of elongation by polymerase, whereas Sp1 and other DNA sequence-specific transcription factors activate the rate of initiation. Furthermore, while TATA binding protein (TBP)-associated factors (TAFs) in the TFIID complex are required for activation by transcription factors, they are dispensable for Tat function. Thus, Tat acts through a novel mechanism, which is mediated by a specific host cellular factor, to stimulate HIV-1 gene expression.
Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139.
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D005656:Fungal Proteins / Q000378:metabolism; D015967:Gene Expression Regulation, Viral; D015696:Gene Products, tat / Q000502:physiology*; D015497:HIV-1 / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D054322:tat Gene Products, Human Immunodeficiency Virus
D005656:Fungal Proteins; C070633:Gal-VP16; D015696:Gene Products, tat; D015534:Trans-Activators; D014157:Transcription Factors; D054322:tat Gene Products, Human Immunodeficiency Virus