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Letters to Nature

Nature 379, 746-749 (22 February 1996) | doi:10.1038/379746a0; Accepted 26 January 1996

RNA binding and translational suppression by bicoid

Rolando Rivera-Pomar*, Dierk Niessing*, Urs Schmidt-Ott*, Walter J. Gehring† & Herbert Jacklë*

  1. * Abteilung Molekulare Entwicklungsbiologie, Max-Planck-lnstitut für biophysikalische Chemie, Am Fassberg, D-37077 Göttingen, Germany
  2. † Biozentrum der Universität Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
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THE anterior determinant bicoid (bcd) of Drosophila is a homeo-domain protein. It forms an anterior-to-posterior gradient in the embryo and activates, in a concentration-dependent manner, several zygotic segmentation genes during blastoderm formation1–4. Its posterior counterpart, the homeodomain transcription factor caudal (cad)5–7, forms a concentration gradient in the opposite direction, emanating from evenly distributed messenger RNA in the egg. In embryos lacking bed activity as a result of mutation, the cad gradient fails to form and cad becomes evenly distributed throughout the embryo8. This suggests that bed may act in the region-specific control of cad mRNA translation. Here we report that bed binds through its homeodomain to cad mRNA in vitro, and exerts translational control through a bed-binding region of cad mRNA.

Maternal cad mRNA is evenly distributed in the early cleavage-stage embryo (Fig. la), and cad forms a posterior-to-anterior concentration gradient before the initiation of zygotic gene expression67 (Fig.