title: Molecular recognition of the human coactivator CBP by the HIV-1 transcriptional activator Tat.
abstract: HIV-1 Tat is required for the expression of the viral genome. Tat binds to an RNA stem-loop and mediates the recruitment of human coactivators to facilitate HIV-1 transcription. The coactivator and acetyltransferase CREB binding protein (CBP), and the paralog p300, are recruited to the HIV-1 promoter by Tat. Here we identify the interacting domains of Tat and CBP. Circular dichroism and pulldown assays show that full-length Tat binds to the KIX domain of CBP, but not to the C/H1 or CR2 domains. Circular dichroism and NMR studies of Tat deletion mutants localize the KIX-binding domain of Tat to the N-terminal 24 residues of Tat. Transient cotransfections demonstrate that exogenous KIX behaves as a dominant negative to Tat-mediated transcription in human T-cells, suggesting that Tat and KIX interact in vivo. These findings indicate that Tat targets the KIX domain of CBP and provide insight into the molecular interactions involved in regulating HIV-1 gene expression.
authors.affiliation: Department of Biochemistry and Molecular Biology, Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1870, USA.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Vendel
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Lumb
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D050882:CREB-Binding Protein; D002942:Circular Dichroism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D050881:E1A-Associated p300 Protein; D015696:Gene Products, tat / Q000737:chemistry / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D016547:Kinesins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D011485:Protein Binding / Q000235:genetics; D017510:Protein Folding; D017433:Protein Structure, Secondary / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism / Q000502:physiology; D013601:T-Lymphocytes / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D015533:Transcriptional Activation / Q000235:genetics; D054322:tat Gene Products, Human Immunodeficiency Virus
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D015696:Gene Products, tat; C098764:KIF22 protein, human; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D054322:tat Gene Products, Human Immunodeficiency Virus; D050882:CREB-Binding Protein; C494363:CREBBP protein, human; C494364:Crebbp protein, mouse; D050881:E1A-Associated p300 Protein; C494361:Ep300 protein, mouse; D016547:Kinesins