Evidence that SNF2/SWI2 and SNF5 activate transcription in yeast by altering chromatin structure.
Changes in chromatin structure have frequently been correlated with changes in transcription. However, the cause-and-effect relationship between chromatin structure and transcription has been hard to determine. In addition, identifying the proteins that regulate chromatin structure has been difficult. Recent evidence suggests that a functionally related set of yeast transcriptional activators (SNF2/SWI2, SNF5, SNF6, SWI1, and SWI3), required for transcription of a diverse set of genes, may affect chromatin structure. We now present genetic and molecular evidence that at least two of these transcriptional activators, SNF2/SWI2 and SNF5, function by antagonizing repression mediated by nucleosomes. First, the transcriptional defects in strains lacking these SNF genes are suppressed by a deletion of one of the two sets of genes encoding histones H2A and H2B, (hta1-htb1) delta. Second, at one affected promoter (SUC2), chromatin structure is altered in snf2/swi2 and snf5 mutants, and this chromatin defect is suppressed by (hta1-htb1) delta. Finally, analysis of chromatin structure at a mutant SUC2 promoter, in which the TATA box has been destroyed, demonstrates that the differences in SUC2 chromatin structure between SNF5+ and snf5 mutant strains are not simply an effect of different levels of SUC2 transcription. Thus, these results strongly suggest that SNF2/SWI2 and SNF5 cause changes in chromatin structure and that these changes allow transcriptional activation.
Hirschhorn
J N
JN
Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115.
Brown
S A
SA
Clark
C D
CD
Winston
F
F
D000251:Adenosine Triphosphatases; D001483:Base Sequence; D002843:Chromatin / Q000378:metabolism* / Q000648:ultrastructure; D002868:Chromosomal Proteins, Non-Histone; D004271:DNA, Fungal; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D006657:Histones / Q000235:genetics; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D000071796:SMARCB1 Protein; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D013489:Suppression, Genetic; D016385:TATA Box; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D006657:Histones; D009687:Nuclear Proteins; D000071796:SMARCB1 Protein; C513266:SMARCB1 protein, human; C066190:SNF5 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000251:Adenosine Triphosphatases; C499333:SNF2 protein, S cerevisiae