The bovine leukemia virus tax gene contains an enhancer sequence.
Transactivator proteins of the bovine leukemia (BLV) and human T-lymphotropic (HTLV) viruses increase long terminal repeat (LTR)-directed viral gene expression and act as immortalizing oncogenes in tissue culture. We report here that the BLV tax gene sequence contains an enhancer-like activity. The X long open reading frame was cloned up-stream of the beta-globin promoter linked to the chloramphenicol acetyltransferase (CAT) gene. In the presence of tax sequences, up to sevenfold enhancement of CAT expression was observed. A computer-assisted homology search revealed the presence of a consensus enhancer core sequence (GTGTTGTTGGTTG) into the third exon of the 2.1-kb X mRNA. These studies demonstrate that the tax gene contains a transcriptional enhancer which could be involved in early viral gene expression in vivo.
Willems
L
L
Department of Molecular Biology, Faculty of Agronomy, Gembloux, Belgium.
Romond
P C
PC
Ghysdael
J
J
Burny
A
A
Kettmann
R
R
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D004279:DNA, Viral / Q000235:genetics; D004742:Enhancer Elements, Genetic; D015967:Gene Expression Regulation, Viral; D016356:Gene Products, tax / Q000235:genetics*; D006801:Humans; D001909:Leukemia Virus, Bovine / Q000235:genetics*; D008969:Molecular Sequence Data; D013329:Structure-Activity Relationship
D004279:DNA, Viral; D016356:Gene Products, tax