Abstract
The Drosophila homeodomain protein Even-skipped (Eve) is a well characterized transcriptional repressor. Here, we show that Eve's ability to function in vitro is negatively regulated by phosphorylation. DNA-binding activity was unaffected by phosphorylation, but phosphorylated Eve was unable to interact with the TATA-binding protein (TBP), a known target for repression. Unexpectedly, phosphorylation of the Eve N terminus, which is dispensable for repression and TBP binding, was necessary and sufficient to inactivate Eve. LiCl, which specifically inhibits glycogen synthase kinase-3 (GSK-3), reduced Eve phosphorylation in nuclear extract and blocked inhibition of repression. In addition, Eve was phosphorylated and inactivated by purified GSK-3 beta plus casein kinase II. Our results suggest a novel mechanism of transcriptional control involving phosphorylation-induced allosteric interference with a repressive protein-protein interaction.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Allosteric Regulation / genetics
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Animals
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Bacterial Proteins*
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Calcium-Calmodulin-Dependent Protein Kinases / metabolism
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Casein Kinase II
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DNA-Binding Proteins / metabolism
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Drosophila / genetics*
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Drosophila Proteins*
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Glycogen Synthase Kinase 3
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Glycogen Synthase Kinases
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Homeodomain Proteins / genetics*
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Homeodomain Proteins / metabolism
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Lithium / pharmacology
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Phosphorylation
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Protein Serine-Threonine Kinases / metabolism
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Repressor Proteins / genetics*
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TATA-Box Binding Protein
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Trans-Activators / metabolism
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Transcription Factors / genetics
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Transcription Factors / metabolism
Substances
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Bacterial Proteins
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DNA-Binding Proteins
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Drosophila Proteins
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Homeodomain Proteins
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Repressor Proteins
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TATA-Box Binding Protein
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Trans-Activators
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Transcription Factors
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bcd protein, Drosophila
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eve protein, Drosophila
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Lithium
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Glycogen Synthase Kinases
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Casein Kinase II
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Protein Serine-Threonine Kinases
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Sgg protein, Drosophila
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Calcium-Calmodulin-Dependent Protein Kinases
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Glycogen Synthase Kinase 3