Abstract
Previous studies have identified two corepressors in the early Drosophila embryo: Groucho and dCTBP: Both proteins are recruited to the DNA template by interacting with short peptide motifs conserved in a variety of sequence-specific transcriptional repressors. Once bound to DNA, Groucho appears to mediate long-range repression, while dCtBP directs short-range repression. The short-range Krüppel repressor was converted into a long-range repressor by replacing the dCtBP interaction motif (PxDLSxH) with a Groucho motif (WRPW). The resulting chimeric repressor causes a different mutant phenotype from that of the native Krüppel protein when misexpressed in transgenic embryos. The different patterning activities can be explained on the basis of long-range silencing within the hairy 5' regulatory region. The analysis of a variety of synthetic transgenes provides evidence that Groucho-dependent long-range repressors do not always cause the dominant silencing of linked enhancers within a complex cis-regulatory region. We suggest a "hot chromatin" model, whereby repressors require activators to bind DNA.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Alcohol Oxidoreductases
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Amino Acid Motifs / physiology
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Animals
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Basic Helix-Loop-Helix Transcription Factors
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Body Patterning / genetics
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DNA / metabolism
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Drosophila
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Drosophila Proteins*
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Embryo, Nonmammalian / metabolism
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Enhancer Elements, Genetic
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Gene Silencing
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Genes, Dominant
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Insect Proteins / genetics
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Kruppel-Like Transcription Factors
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Models, Genetic
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Phenotype
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Phosphoproteins / metabolism*
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Regulatory Sequences, Nucleic Acid
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Repressor Proteins / genetics
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Repressor Proteins / metabolism*
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Snail Family Transcription Factors
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Transcription Factors / genetics
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Transgenes
Substances
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Basic Helix-Loop-Helix Transcription Factors
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DNA-Binding Proteins
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Drosophila Proteins
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Insect Proteins
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Kr protein, Drosophila
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Kruppel-Like Transcription Factors
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Phosphoproteins
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Recombinant Fusion Proteins
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Repressor Proteins
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Snail Family Transcription Factors
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Transcription Factors
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gro protein, Drosophila
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hairy protein, Drosophila
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sna protein, Drosophila
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hairy protein, insect
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DNA
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Alcohol Oxidoreductases
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C-terminal binding protein