title: Sequence interval within the PEST motif of Bicoid is important for translational repression of caudal mRNA in the anterior region of the Drosophila embryo.
abstract: 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 embryo. 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.
authors: Max-Planck-Institut für biophysikalische Chemie, Abt. Molekulare Entwicklungsbiologie, Am Fassberg, D-37077 Göttingen, Germany.
authors: D
authors: D
authors: Niessing
authors: N
authors: N
authors: Dostatni
authors: H
authors: H
authors: Jäckle
authors: R
authors: R
authors: Rivera-Pomar
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D004330:Drosophila / Q000196:embryology / Q000235:genetics* / Q000378:metabolism*; D029721:Drosophila Proteins; D005260:Female; D017344:Genes, Insect; D006257:Head / Q000196:embryology; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013489:Suppression, Genetic; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014157:Transcription Factors; D014162:Transfection
chemical_list: D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D019476:Insect Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C056478:bcd protein, Drosophila; C084564:cad protein, Drosophila