Abstract
The yeast HO gene is transcribed transiently during G1 as cells undergo START. START-specific HO activation requires two proteins, SWI4 and SWI6, which act via a motif (CACGA4) repeated up to 10 times within the URS2 region of the HO promoter. We identified a DNA-binding activity containing SWI4 and SWI6 that recognizes the CACGA4 sequences within URS2. Two forms of SWI4,6-DNA complexes called L and U can be distinguished by their electrophoretic mobility. L complexes can be detected at all stages of the cell cycle, but U complexes are only detected in cells that have undergone START. The formation of U complexes may be the trigger of HO activation. The SWI6 protein is concentrated in the nucleus throughout G1, but at some point in S or G2 significant amounts accumulate in the cytoplasm. This change in cellular location of the SWI6 protein might contribute to the turnoff of HO transcription after cells have undergone START.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Base Sequence
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Cell Cycle / genetics
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DNA, Fungal / metabolism*
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Deoxyribonucleases, Type II Site-Specific / genetics*
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Fungal Proteins / genetics
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Fungal Proteins / metabolism*
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Gene Expression Regulation, Fungal / physiology*
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Genes, Fungal / genetics
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Kinetics
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Molecular Sequence Data
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Precipitin Tests
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Promoter Regions, Genetic / genetics
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Protein Kinases / metabolism
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Repetitive Sequences, Nucleic Acid / genetics
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Saccharomyces cerevisiae / genetics*
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Saccharomyces cerevisiae Proteins*
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Transcription Factors / genetics
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Transcription Factors / metabolism
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Transcriptional Activation
Substances
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DNA, Fungal
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DNA-Binding Proteins
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Fungal Proteins
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SWI4 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Transcription Factors
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Protein Kinases
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HO protein, S cerevisiae
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SCEI protein, S cerevisiae
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Deoxyribonucleases, Type II Site-Specific