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Sequence interval within the PEST motif of Bicoid is important for translational repression of caudal mRNA in the anterior region of the Drosophila embryo
Author(s) -
Niessing Dierk,
Dostatni Nathalie,
Jäckle Herbert,
RiveraPomar Rolando
Publication year - 1999
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/18.7.1966
Subject(s) - biology , drosophila embryogenesis , genetics , psychological repression , embryo , motif (music) , microbiology and biotechnology , messenger rna , drosophila (subgenus) , sequence (biology) , embryogenesis , gene , gene expression , physics , acoustics
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.