Photofootprinting in vivo of GALl 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.
Copyright © 1993 Cold Spring Harbor Laboratory Press. This article is distributed under the Creative Commons Attribution-Non-Commercial 3.0 Unported License (CC-BY-NC), as described at http://creativecommons.org/licenses/by-nc/3.0/. This license permits non-commercial use, including reproduction, adaptation, and distribution of the article provided the original author and source are credited.
Axelrod JD, Reagan MS, Majors J. 1993. GAL4 disrupts a repressing nucleosome during activation of GAL1 transcription in vivo. Genes & Development 7(5): 857-869.