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.
Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110.
J D
JD
Axelrod
M S
MS
Reagan
J
J
Majors
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