RT Journal Article
SR Electronic
T1 Concentration Dependent Chromatin States Induced by the Bicoid Morphogen Gradient
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 133348
DO 10.1101/133348
A1 Colleen E. Hannon
A1 Shelby A. Blythe
A1 Eric F. Wieschaus
YR 2017
UL http://biorxiv.org/content/early/2017/05/03/133348.abstract
AB In Drosophila, graded expression of the maternal transcription factor Bicoid (Bcd) provides positional information to activate target genes at different positions along the anterior-posterior axis. We have measured the genome-wide binding profile of Bcd using ChIP-seq in embryos expressing single, uniform levels of Bcd protein, and grouped Bcd-bound targets into four classes based on occupancy at different concentrations. By measuring the biochemical affinity of target enhancers in these classes in vitro and genome-wide chromatin accessibility by ATAC-seq, we found that the occupancy of target sequences by Bcd is not primarily determined by Bcd binding sites, but by chromatin context. Bcd drives an open chromatin state at a subset its targets. Our data support a model where Bcd influences chromatin structure to gain access to concentration-sensitive targets at high concentrations, while concentration-insensitive targets are found in more accessible chromatin and are bound at low concentrations.