Mechanism of synergy between TATA and initiator: synergistic binding of TFIID following a putative TFIIA-induced isomerization

  1. Katayoon H. Emami1,2,
  2. Anjali Jain2, and
  3. Stephen T. Smale3
  1. Howard Hughes Medical Institute, Molecular Biology Institute, and Department of Microbiology and Immunology, University of California, Los Angeles, School of Medicine, Los Angeles, California 90095-1662 USA

Abstract

The TFIID complex interacts with at least three types of core promoter elements within protein-coding genes, including TATA, initiator (Inr), and downstream promoter elements. We have begun to explore the mechanism by which the TFIID–Inr interaction leads to functional synergy between TATA and Inr elements during both basal and activated transcription. In DNase I footprinting assays, GAL4–VP16 recruited TFIID–TFIIA to core promoters containing either a TATA box, an Inr, or both TATA and Inr elements, with synergistic interactions apparent on the TATA–Inr promoter. Appropriate spacing between the two elements was essential for the synergistic binding. Despite the sequence-specific TFIID–Inr interactions, gel shift experiments revealed that TFIID alone possesses similar affinities for the TATA–Inr and TATA promoters. Interestingly, however, recombinant TFIIA strongly and selectively enhanced TFIID binding to the TATA–Inr promoter, with little effect on binding to the TATA promoter. Studies of the natural adenovirus major late promoter confirmed these findings, despite the existence of specific but nonfunctional TFIID interactions downstream of the Inr in that promoter. These results suggest that a TFIIA-induced conformational change is essential for the sequence-specific TFIID–Inr interaction to occur with sufficient affinity to support the functional synergism between TATA and Inr elements.

Keywords

Footnotes

  • 1 Present address: Division of Biology, California Institute of Technology, Pasadena, California 91125 USA.

  • 2 These authors contributed equally to this work.

  • 3 Corresponding author.

  • E-MAIL steves{at}hhmi.ucla.edu; FAX (310) 206-8623.

    • Received July 22, 1997.
    • Accepted September 29, 1997.
| Table of Contents

Life Science Alliance