Molecular Recognition of the Human Coactivator CBP by the HIV-1 Transcriptional Activator Tat

• Published in: Biochemistry (Easton) 2003-02, Vol.42 (4), p.910-916
• Main Authors: Vendel, Andrew C, Lumb, Kevin J
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Circular Dichroism; CREB-Binding Protein; Cyclic AMP Response Element-Binding Protein - metabolism; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; DNA-Binding Proteins - physiology; E1A-Associated p300 Protein; Gene Products, tat - chemistry; Gene Products, tat - metabolism; HIV-1 - metabolism; Humans; Jurkat Cells; Kinesin - genetics; Kinesin - metabolism; Kinesin - physiology; Mice; Molecular Sequence Data; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; Nuclear Proteins - physiology; Protein Binding - genetics; Protein Folding; Protein Structure, Secondary - genetics; Protein Structure, Tertiary - genetics; Recombinant Fusion Proteins - metabolism; Recombinant Fusion Proteins - physiology; T-Lymphocytes - metabolism; tat Gene Products, Human Immunodeficiency Virus; Trans-Activators - genetics; Trans-Activators - metabolism; Trans-Activators - physiology; Transcriptional Activation - genetics
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi0270034

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.