View the Current Issue

Article

  • The EMBO Journal (1999) 18, 5073 - 5084
  • doi:10.1093/emboj/18.18.5073

New mode of DNA binding of multi-zinc finger transcription factors: deltaEF1 family members bind with two hands to two target sites

Jacques E. Remacle1, Harry Kraft1, Walter Lerchner2, Gunther Wuytens1, Clara Collart1, Kristin Verschueren1, James C. Smith2 and Danny Huylebroeck1

  1. Department of Cell Growth, Differentiation and Development (VIB-07), Flanders Interuniversity Institute for Biotechnology (VIB) and Laboratory of Molecular Biology (CELGEN), University of Leuven, Herestraat 49, B-3000 Leuven, Belgium
  2. Division of Developmental Biology, National Institute for Medical Research, The Ridgeway, London NW7 1AA, UK

Correspondence to:

Danny Huylebroeck, E-mail: dhu@sgi.celgen.kuleuven.ac.be

Received 19 May 1999; Accepted 27 July 1999; Revised 21 June 1999

SIP1, a Smad-interacting protein, and deltaEF1, a transcriptional repressor involved in skeletal and T-cell development, belong to the same family of DNA binding proteins. SIP1 and deltaEF1 contain two separated clusters of zinc fingers, one N-terminal and one C-terminal. These clusters show high sequence homology and are highly conserved between SIP1 and deltaEF1. Each zinc finger cluster binds independently to a 5'-CACCT sequence. However, high-affinity binding sites for full-length SIP1 and deltaEF1 in the promoter regions of candidate target genes like Xenopus Xbra2, and human alpha4-integrin and E-cadherin, are bipartite elements composed of one CACCT and one CACCTG sequence, the orientation and spacing of which can vary. Using transgenic Xenopus embryos, we demonstrate that the integrity of these two sequences is necessary for correct spatial expression of a Xbra2 promoter-driven reporter gene. Both zinc finger clusters must be intact for the high-affinity binding of SIP1 to DNA and for its optimal repressor activity. Our results show that SIP1 binds as monomer and contacts one target sequence with the first zinc finger cluster, and the other with the second cluster. Our work redefines the optimal binding site and, consequently, candidate target genes for vertebrate members of the deltaEF1 family.

  • Keywords:

    • deltaEF1,
    • Smad-interacting protein,
    • Smad proteins,
    • transgenic Xenopus,
    • two-handed zinc finger proteins