title: Hepatitis B virus transactivator protein X interacts with the TATA-binding protein.
abstract: Several viral transcriptional activators have been shown to interact with the basal transcription factor TATA-binding protein (TBP). These associations have been implicated in facilitating the assembly of the transcriptional preinitiation complex. We report here that the hepatitis B virus protein X (pX) specifically binds to TBP in vitro. While truncations of the highly conserved carboxyl terminus of TBP abolished this binding, amino-terminal deletions had no effect. Deletion analysis suggests that a domain consisting of 71 aa in the highly conserved carboxyl-terminal region of TBP is necessary for its interaction with pX. The minimal region in pX sufficient for its interaction with TBP includes aa 110-143. Furthermore, TBP from phylogenetically distinct species including Arabidopsis thaliana, Saccharomyces cerevisiae, Drosophila melanogaster, and Solanum tuberosum (potato) bound to pX. The pX-TBP interaction was inhibited in the presence of nonhydrolyzable analogs of ATP, suggesting a requirement for ATP. These results provide an explanation for the promiscuous behavior of pX in the transactivation of a large repertoire of cellular promoters. This study further implicates a fundamental role for pX in modulating transcriptional regulatory pathways by interacting with the basal transcription factor TBP.
authors.affiliation: Department of Microbiology, University of Colorado Health Sciences Center, Denver 80262.
authors.forename: I
authors.initials: I
authors.lastname: Qadri
authors.forename: H F
authors.initials: HF
authors.lastname: Maguire
authors.forename: A
authors.initials: A
authors.lastname: Siddiqui
mesh_terms: D000595:Amino Acid Sequence; D017124:Conserved Sequence; D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006511:Hepatitis B Antigens / Q000378:metabolism*; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D016385:TATA Box; D035181:TATA-Box Binding Protein; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D006511:Hepatitis B Antigens; D035181:TATA-Box Binding Protein; D015534:Trans-Activators; D014157:Transcription Factors; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein