Transcriptional activation of the human immunodeficiency virus type 1 long terminal repeat by hepatitis B virus X-protein requires de novo protein synthesis.
Human hepatitis B virus (HBV) X-gene, previously shown to be capable of trans-activating heterologous regulatory elements of the human beta-interferon gene, the human immunodeficiency virus type I (HIV-1) long terminal repeat (LTR), the simian virus 40 (SV40), and HBV, has the capacity to code for a 17-kDa polypeptide (designated pX17). We now report that pX17 synthesized in Escherichia coli can activate transcription controlled by the HIV-1 LTR using a protoplast fusion technique. Protoplasts of E. coli-containing presynthesized X-protein were fused with lymphocytic H938 cells harboring an integrated copy of a plasmid with the CAT gene under control of the HIV-1 LTR (HIV-1 LTR CAT) and a marked increase in the steady state expression of the CAT mRNA was observed. When the same fused cells were treated with the protein synthesis inhibitor cyclohexamide, the pX17-dependent activation of the HIV-1 LTR was abolished. This result indicates that the X-protein expressed in E. coli is biologically active and suggests that the HBV X-protein-mediated trans-activation of the HIV-1 LTR in this system requires de novo cellular protein synthesis.
Department of Medicine, Stanford University School of Medicine, California 94305.
J S
JS
Twu
J Y
JY
Wu
W S
WS
Robinson
D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis / Q000235:genetics; D003001:Cloning, Molecular; D003513:Cycloheximide / Q000494:pharmacology*; D004926:Escherichia coli / Q000235:genetics; D015497:HIV-1 / Q000235:genetics*; D006515:Hepatitis B virus / Q000235:genetics; D008970:Molecular Weight; D010957:Plasmids; D011523:Protoplasts / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D015534:Trans-Activators / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation / Q000187:drug effects; D054334:Viral Regulatory and Accessory Proteins
D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein; D003513:Cycloheximide; D015500:Chloramphenicol O-Acetyltransferase