title: Hepatitis B virus X protein transactivates the long terminal repeats of human immunodeficiency virus types 1 and 2.
abstract: The X gene product of the hepatitis B virus (HBV) has been expressed transiently in HepG2 cells, and the 17-kilodalton protein has been detected by Western (immuno-) blot analysis. Cotransfection of the X gene with the long terminal repeat of human immunodeficiency virus type 1 or 2 results in a stimulation of long terminal repeat-directed expression that is higher than the X-induced stimulation of the HBV enhancer linked to either autologous promoter or to the heterologous simian virus 40 promoter. A frameshift mutation abolished this transactivation. In vitro nuclear transcription assays revealed that HBV X acts at the transcriptional level. The carboxy terminus of the HBV X protein does not seem to be necessary for its transactivating activity, as demonstrated by using HBV X protein deletion mutants.
authors.affiliation: I Clinica Medica, Università di Roma La Sapienza, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Levrero
authors.forename: C
authors.initials: C
authors.lastname: Balsano
authors.forename: G
authors.initials: G
authors.lastname: Natoli
authors.forename: M L
authors.initials: ML
authors.lastname: Avantaggiati
authors.forename: E
authors.initials: E
authors.lastname: Elfassi
mesh_terms: D015153:Blotting, Western; D002460:Cell Line; D002872:Chromosome Deletion; D004742:Enhancer Elements, Genetic; D005814:Genes, Viral; D015497:HIV-1 / Q000235:genetics*; D015498:HIV-2 / Q000235:genetics*; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D009154:Mutation; D010957:Plasmids; D012091:Repetitive Sequences, Nucleic Acid; D015534:Trans-Activators / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein