HTLV-I Tax protein stimulation of DNA binding of bZIP proteins by enhancing dimerization.
The Tax protein of human T cell leukemia virus type-1 (HTLV-I) transcriptionally activates the HTLV-I promoter. This activation requires binding sites for activating transcription factor (ATF) proteins, a family of cellular proteins that contain basic region-leucine zipper (bZIP) DNA binding domains. Data are presented showing that Tax increases the in vitro DNA binding activity of multiple ATF proteins. Tax also stimulated DNA binding by other bZIP proteins, but did not affect DNA binding proteins that lack a bZIP domain. The increase in DNA binding occurred because Tax promotes dimerization of the bZIP domain in the absence of DNA, and the elevated concentration of the bZIP homodimer then facilitates the DNA binding reaction. These results help explain how Tax activates viral transcription and transforms cells.
Wagner
S
S
Program in Molecular Medicine, University of Massachusetts Medical Center, Worcester 01605.
Green
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MR
D051697:Activating Transcription Factor 1; D051698:Activating Transcription Factor 2; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors; D001665:Binding Sites; D002460:Cell Line; D002472:Cell Transformation, Viral; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins; D051790:G-Box Binding Factors; D016356:Gene Products, tax / Q000378:metabolism*; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000378:metabolism*; D010940:Plant Proteins; D011108:Polymers; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
D051697:Activating Transcription Factor 1; D051698:Activating Transcription Factor 2; D050976:Basic-Leucine Zipper Transcription Factors; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D051790:G-Box Binding Factors; D016356:Gene Products, tax; D009838:Oligodeoxyribonucleotides; D010940:Plant Proteins; D011108:Polymers; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D004247:DNA