Recognition of bZIP proteins by the human T-cell leukaemia virus transactivator Tax.
Human T-cell leukaemia virus type I (HTLV-I) Tax protein increases the DNA binding of many cellular transcription factors that contain a basic region-leucine zipper (bZIP) DNA-binding domain. bZIP domains comprise a leucine-rich dimerization motif and a basic region that mediates DNA contact. How Tax recognizes diverse bZIPs is not understood. Here we show that no specific sequence of the leucine zipper is required for a Tax response. In contrast, the basic region is essential for the Tax-mediated DNA-binding increase, which can be eliminated by single substitutions of several conserved amino acids. Surprisingly, Tax alters the relative affinity of a bZIP for different DNA binding sites. Thus, through recognition of the conserved basic region. Tax increases DNA binding and modifies DNA site selection. Tax provides a model for how a single auxiliary factor can regulate multiple sequence-specific DNA-binding proteins.
Perini
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G
Howard Hughes Medical Institute, University of Massachusetts Medical Center, Worcester 01605, USA.
Wagner
S
S
Green
M R
MR
D000595:Amino Acid Sequence; D001483:Base Sequence; D016384:Consensus Sequence; D004247:DNA / Q000378:metabolism; D015342:DNA Probes; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D016356:Gene Products, tax / Q000378:metabolism*; D015368:Human T-lymphotropic virus 1 / Q000378:metabolism*; D007930:Leucine / Q000378:metabolism; D016350:Leucine Zippers / Q000235:genetics; D008969:Molecular Sequence Data; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins
D015342:DNA Probes; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D016356:Gene Products, tax; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; D011494:Protein Kinases; D007930:Leucine