GAL4 disrupts a repressing nucleosome during activation of GAL1 transcription in vivo.
Photofootprinting in vivo of GAL1 reveals an activation-dependent pattern between the UASG and the TATA box, in a sequence not required for transcriptional activation by GAL4. The pattern results from a nucleosome whose position depends on sequences within the UASG. In the wild-type gene, activation by GAL4 and derivatives disrupts this nucleosome. This activity is independent of interactions with DNA-bound core transcription factors and is proportional to the strength of the activator. Presence of the nucleosome correlates with low basal transcription levels under various conditions, suggesting a role in limiting basal expression. We propose a role for the GAL4 activation domain in displacing a nucleosome and suggest that this is part of the mechanism by which GAL4 activates transcription in vivo.
Axelrod
J D
JD
Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110.
Reagan
M S
MS
Majors
J
J
D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D004271:DNA, Fungal / Q000032:analysis; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000502:physiology*; D008969:Molecular Sequence Data; D009707:Nucleosomes / Q000502:physiology*; D010957:Plasmids; D011401:Promoter Regions, Genetic / Q000502:physiology; D012331:RNA, Fungal / Q000032:analysis / Q000302:isolation & purification; D012045:Regulatory Sequences, Nucleic Acid; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D016385:TATA Box / Q000502:physiology; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic / Q000502:physiology*
D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; D009707:Nucleosomes; D012331:RNA, Fungal; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors