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1.
Mol Cell Biol ; 21(19): 6450-60, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11533234

ABSTRACT

The yeast Isw2 chromatin remodeling complex functions in parallel with the Sin3-Rpd3 histone deacetylase complex to repress early meiotic genes upon recruitment by Ume6p. For many of these genes, the effect of an isw2 mutation is partially masked by a functional Sin3-Rpd3 complex. To identify the full range of genes repressed or activated by these factors and uncover hidden targets of Isw2-dependent regulation, we performed full genome expression analyses using cDNA microarrays. We find that the Isw2 complex functions mainly in repression of transcription in a parallel pathway with the Sin3-Rpd3 complex. In addition to Ume6 target genes, we find that many Ume6-independent genes are derepressed in mutants lacking functional Isw2 and Sin3-Rpd3 complexes. Conversely, we find that ume6 mutants, but not isw2 sin3 or isw2 rpd3 double mutants, have reduced fidelity of mitotic chromosome segregation, suggesting that one or more functions of Ume6p are independent of Sin3-Rpd3 and Isw2 complexes. Chromatin structure analyses of two nonmeiotic genes reveals increased DNase I sensitivity within their regulatory regions in an isw2 mutant, as seen previously for one meiotic locus. These data suggest that the Isw2 complex functions at Ume6-dependent and -independent loci to create DNase I-inaccessible chromatin structure by regulating the positioning or placement of nucleosomes.


Subject(s)
Adenosine Triphosphatases/physiology , Chromatin/physiology , Gene Expression Regulation, Fungal , Saccharomyces cerevisiae Proteins , Transcription Factors/physiology , Yeasts/genetics , Adenosine Triphosphatases/genetics , Cell Division , Chromatin/ultrastructure , Chromosome Segregation , DNA-Binding Proteins/genetics , DNA-Binding Proteins/physiology , Deoxyribonuclease I/chemistry , Histone Deacetylases , Macromolecular Substances , Mutation , Oligonucleotide Array Sequence Analysis , Phenotype , Repressor Proteins/genetics , Repressor Proteins/physiology , Transcription Factors/genetics , Transcription, Genetic , Yeasts/cytology , Yeasts/metabolism
2.
Cell ; 103(3): 423-33, 2000 Oct 27.
Article in English | MEDLINE | ID: mdl-11081629

ABSTRACT

The ISWI class of chromatin remodeling factors exhibits potent chromatin remodeling activities in vitro. However, the in vivo functions of this class of factors are unknown at a molecular level. We have found that S. cerevisiae Isw2 complex represses transcription of early meiotic genes during mitotic growth in a parallel pathway to Rpd3-Sin3 histone deacetylase complex. This repressor function of lsw2 complex is largely dependent upon Ume6p, which recruits the complex to target genes. Nuclease digestion analyses revealed that lsw2 complex establishes nuclease-inaccessible chromatin structure near the Ume6p binding site in vivo. Based on these findings, we propose a model for the mechanism of transcriptional repression by two distinct chromatin remodeling complexes.


Subject(s)
Chromatin/metabolism , DNA-Binding Proteins/metabolism , Gene Expression Regulation, Fungal , Meiosis/genetics , Repressor Proteins/metabolism , Saccharomyces cerevisiae Proteins , Saccharomyces cerevisiae/genetics , Transcription Factors/metabolism , Binding Sites , Chromatin/chemistry , Chromatin/genetics , DNA, Fungal/genetics , DNA, Fungal/metabolism , DNA-Binding Proteins/genetics , Epistasis, Genetic , Genes, Fungal/genetics , Histone Deacetylases/genetics , Histone Deacetylases/metabolism , Macromolecular Substances , Mitosis/genetics , Models, Genetic , Molecular Conformation , Mutation/genetics , Nuclease Protection Assays , Promoter Regions, Genetic/genetics , Protein Binding , RNA, Fungal/analysis , RNA, Fungal/genetics , RNA, Messenger/analysis , RNA, Messenger/genetics , Repressor Proteins/genetics , Response Elements/genetics , Saccharomyces cerevisiae/cytology , Saccharomyces cerevisiae/enzymology , Saccharomyces cerevisiae/metabolism , Transcription Factors/genetics
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