Abstract
There are several classes of ATP-dependent chromatin remodeling complexes, which modulate the structure of chromatin to regulate a variety of cellular processes. The budding yeast, Saccharomyces cerevisiae, encodes two ATPases of the ISWI class, Isw1p and Isw2p. Previously Isw1p was shown to copurify with three other proteins. Here we identify these associated proteins and show that Isw1p forms two separable complexes in vivo (designated Isw1a and Isw1b). Biochemical assays revealed that while both have equivalent nucleosome-stimulated ATPase activities, Isw1a and Isw1b differ in their abilities to bind to DNA and nucleosomal substrates, which possibly accounts for differences in specific activities in nucleosomal spacing and sliding. In vivo, the two Isw1 complexes have overlapping functions in transcriptional regulation of some genes yet distinct functions at others. In addition, these complexes show different contributions to cell growth at elevated temperatures.
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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Adenosine Triphosphatases / genetics
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Adenosine Triphosphatases / isolation & purification
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Adenosine Triphosphatases / metabolism*
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Amino Acid Motifs
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Amino Acid Sequence
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DNA, Fungal / metabolism
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / isolation & purification
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DNA-Binding Proteins / metabolism*
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Gene Expression Regulation, Fungal
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Macromolecular Substances
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Molecular Sequence Data
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Mutation
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Nucleosomes / metabolism*
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Oligonucleotide Array Sequence Analysis
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Protein Isoforms
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / isolation & purification
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Saccharomyces cerevisiae Proteins / metabolism*
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Sequence Homology, Amino Acid
Substances
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DNA, Fungal
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DNA-Binding Proteins
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IOC2 protein, S cerevisiae
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IOC3 protein, S cerevisiae
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IOC4 protein, S cerevisiae
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Macromolecular Substances
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Nucleosomes
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Protein Isoforms
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Saccharomyces cerevisiae Proteins
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Adenosine Triphosphatases
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ISW1 protein, S cerevisiae