Characterization of cellular factors that interact with the human T-cell leukemia virus type I p40x-responsive 21-base-pair sequence.
Transcriptional activation of the human T-cell leukemia virus type I (HTLV-I) long terminal repeat (LTR) by viral protein p40x requires a 21-base-pair (bp) sequence which is repeated three times within the LTR. This sequence contains a core octanucleotide (TGACGTCT) which has been attributed to be a cyclic-AMP (cAMP)-responsive element. We demonstrate here that the HTLV-I LTR can be specifically stimulated by cAMP regulators and have identified four proteins in HeLa cells that bind to the HTLV-I 21-bp sequence. We correlated the in vitro binding and transcriptional activity of one of these cellular factors (Mr, 180,000) to the trans-activation of the HTLV-I LTR by p40x. Point mutations were generated within the cAMP octanucleotide of the HTLV-I 21-bp sequence that simultaneously abolished biological responsiveness to trans-activation by p40x and to stimulation by cAMP. We found that these mutations also eliminated the binding of the 180-kilodalton HeLa factor to the HTLV-I 21-bp element. In the absence of a demonstrable DNA-binding property for p40x, we hypothesize that cellular proteins are involved, possibly through signal transduction pathways, in its trans-activation of responsive promoters.
Jeang
K T
KT
Laboratory of Molecular Virology, National Cancer Institute, Bethesda, Maryland 20892.
Boros
I
I
Brady
J
J
Radonovich
M
M
Khoury
G
G
D001483:Base Sequence; D015342:DNA Probes; D004279:DNA, Viral / Q000235:genetics*; D004591:Electrophoresis, Polyacrylamide Gel; D005814:Genes, Viral; D015486:HTLV-I Antigens / Q000235:genetics*; D006367:HeLa Cells; D015368:Human T-lymphotropic virus 1 / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D012091:Repetitive Sequences, Nucleic Acid; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic
D015342:DNA Probes; D004279:DNA, Viral; D015486:HTLV-I Antigens; D015534:Trans-Activators; D014157:Transcription Factors