Isolation of cDNAs for DNA-binding proteins which specifically bind to a tax-responsive enhancer element in the long terminal repeat of human T-cell leukemia virus type I.
One of the gene products of human T-cell leukemia virus type I (HTLV-I), p40tax, activates its own viral transcription in trans through tax-responsive enhancers in viral long terminal repeats. Five species of cDNA clones for proteins that bind to the tax-responsive enhancer element in HTLV-I were isolated from the Jurkat cell library. The beta-galactosidase fusion protein prepared from the lysogen of a clone specifically recognized the cyclic AMP-responsive element in HTLV-I enhancer. The nucleotide sequence of a full-length cDNA clone (TAXREB67) had a coding capacity of 351 amino acids, which contained a basic motif followed by a leucine zipper structure near the carboxy terminus. Its mRNA was detected in human cell lines, including HTLV-I-infected or noninfected hematopoietic cell lines. The mRNA level in Jurkat cells was decreased temporarily by increasing cyclic AMP concentration but increased by increasing Ca2+ concentration. Polyclonal antibodies against the fusion protein specifically recognized a 52-kDa protein in Jurkat cells. Analyses of the function of this protein and its interactions with other cellular factors will be useful to help understand the regulatory mechanism through tax-responsive enhancers in HTLV-I.
Tsujimoto
A
A
Virology Division, National Cancer Center Research Institute, Tokyo, Japan.
Nyunoya
H
H
Morita
T
T
Sato
T
T
Shimotohno
K
K
D000595:Amino Acid Sequence; D001483:Base Sequence; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D003001:Cloning, Molecular; D000242:Cyclic AMP / Q000378:metabolism; D004273:DNA, Neoplasm / Q000235:genetics* / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D015723:Gene Library; D016355:Genes, pX; D015368:Human T-lymphotropic virus 1 / Q000235:genetics*; D006801:Humans; D015151:Immunoblotting; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D014158:Transcription, Genetic / Q000187:drug effects; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D003994:Bucladesine; D000242:Cyclic AMP; D001616:beta-Galactosidase; D002118:Calcium