Abstract
Chromatin organization is highly dynamic and regulates transcription. Upon transcriptional activation, chromatin is remodeled and referred to as “open”, but quantitative and dynamic data of this decompaction process are lacking. Here, we have developed a quantitative superresolution microscopy assay in living yeast cells to visualize chromatin decompaction using the GAL7-10-1 locus as a model system. Upon transcriptional activation of these three clustered genes, we detect an increase of the mean distance across this locus by ~100 nm. This decompaction is linked to active transcription but is not sensitive to the histone deacetylase inhibitor trichostatin A or to deletion of the histone acetyl transferase Gcn5. By contrast, the deletion of SNF2 (encoding the ATPase of the SWI/SNF chromatin remodeling complex) or the deactivation of the histone chaperone complex FACT lead to a strongly reduced decompaction. Our assay quantifies and visualizes for the first time the chromatin conformation changes brought about by transcriptional activation and suggests that nucleosome remodeling and eviction activities are major contributors to chromatin reorganization.
- TSA
- trichostatin A
- ORF
- open reading frame
- qPCR
- quantitative
- PCR SE
- standard error
- SPB
- spindle pole body
- GST
- Glutathione S transferase
- smFISH
- single molecule fluorescence in situ hybridization
- Pol II
- RNA polymerase II