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  • The EMBO Journal (1999) 18, 1966 - 1973
  • doi:10.1093/emboj/18.7.1966

Sequence interval within the PEST motif of Bicoid is important for translational repression of caudal mRNA in the anterior region of the Drosophila embryo

Dierk Niessing1, Nathalie Dostatni2, Herbert Jäckle1 and Rolando Rivera-Pomar3

  1. Max-Planck-Institut für biophysikalische Chemie, Abt. Molekulare Entwicklungsbiologie, Am Fassberg, D-37077 Göttingen, Germany
  2. Institut de Biologie du Développement de Marseille, Campus de Luminy case 907, F-13288 Marseille Cedex 9, France
  3. Present address: Max-Planck-Institut für biophysikalische Chemie, Abt. Molekulare Biologie, Am Fassberg, D-37077 Göttingen, Germany

Correspondence to:

Herbert Jäckle, E-mail: hjaeckl@gwdg.de

Rolando Rivera-Pomar, E-mail: roland@mpc186.mpibpc.gwdg.de

Received 15 December 1998; Accepted 12 February 1999; Revised 12 February 1999

The Drosophila body organizer Bicoid (Bcd) is a maternal homeodomain protein. It forms a concentration gradient along the longitudinal axis of the preblastoderm embryo and activates early zygotic segmentation genes in a threshold-dependent fashion. In addition, Bcd acts as a translational repressor of maternal caudal (cad) mRNA in the anterior region of the embry o. This process involves a distinct Bcd-binding region (BBR) in the 3' untranslated region (UTR) of cad mRNA. Using cotransfection assays, we found that Bcd represses translation in a cap-dependent manner. Bcd-dependent translational repression involves a portion of the PEST motif of Bcd, a conserved protein motif best known for its function in protein degradation. Rescue experiments with Bcd-deficient embryos expressing transgene-derived Bcd mutants indicate that amino acid replacements within the C-terminal portion of the PEST motif prevent translational repression of cad mRNA but allow for Bcd-dependent transcriptional activation. Thus, Bcd contains separable protein domains for transcriptional and translational regulation of target genes. Maternally-derived cad protein in the anterior region of embryos interferes with head morphogenesis, showing that cad mRNA suppression by Bcd is an important control event during early Drosophila embryogenesis.

  • Keywords:

    • Bicoid,
    • cap-dependence,
    • head morphogenesis,
    • PEST,
    • translational control