In vitro selection of DNA elements highly responsive to the human T-cell lymphotropic virus type I transcriptional activator, Tax

S. Paca-Uccaralertkun, L. J. Zhao, N. Adya, J. V. Cross, B. R. Cullen, I. M. Boros, C. Z. Giam

Research output: Contribution to journalArticle

93 Citations (Scopus)

Abstract

The human T-cell lymphotropic virus type I (HTLV-I) transactivator, Tax, the ubiquitous transcriptional factor cyclic AMP (cAMP) response element- binding protein (CREB protein), and the 21-bp repeats in the HTLV-I transcriptional enhancer form a ternary nucleoprotein complex (L. J. Zhao and C. Z. Giam, Proc. Natl. Acad. Sci. USA 89:7070-7074, 1992). Using an antibody directed against the COOH-terminal region of Tax along with purified Tax and CREB proteins, we selected DNA elements bound specifically by the Tax-CREB complex in vitro. Two distinct but related groups of sequences containing the cAMP response element (CRE) flanked by long runs of G and C residues in the 5' and 3' regions, respectively, were preferentially recognized by Tax-CREB. In contrast, CREB alone binds only to CRE motifs (GNTGACG[T/C]) without neighboring G- or C-rich sequences. The Tax-CREB-selected sequences bear a striking resemblance to the 5' or 3' two-thirds of the HTLV-I 21-bp repeats and are highly inducible by Tax. Gel electrophoretic mobility shift assays, DNA transfection, and DNase I footprinting analyses indicated that the G- and C-rich sequences flanking the CRE motif are crucial for Tax-CREB-DNA ternary complex assembly and Tax transactivation but are not in direct contact with the Tax-CREB complex. These data show that Tax recruits CREB to form a multiprotein complex that specifically recognizes the viral 21-bp repeats. The expanded DNA binding specificity of Tax-CREB and the obligatory role the ternary Tax-CREB-DNA complex plays in transactivation reveal a novel mechanism for regulating the transcriptional activity of leucine zipper proteins like CREB.

Original languageEnglish
Pages (from-to)456-462
Number of pages7
JournalMolecular and cellular biology
Volume14
Issue number1
Publication statusPublished - Jan 1 1994

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'In vitro selection of DNA elements highly responsive to the human T-cell lymphotropic virus type I transcriptional activator, Tax'. Together they form a unique fingerprint.

  • Cite this

    Paca-Uccaralertkun, S., Zhao, L. J., Adya, N., Cross, J. V., Cullen, B. R., Boros, I. M., & Giam, C. Z. (1994). In vitro selection of DNA elements highly responsive to the human T-cell lymphotropic virus type I transcriptional activator, Tax. Molecular and cellular biology, 14(1), 456-462.