Fig. 7: Superhelical chromatin buffering.
From: Osmotic disruption of chromatin induces Topoisomerase 2 activity at sites of transcriptional stress
Transcribing RNA polymerases (green ovals) generate torsion in DNA that is largely buffered by higher-order structural rearrangements in the chromatin fibre. Acute osmotic shock disrupts this paradigm, via a rapid and transient fluctuation in nuclear ionic forces that alters the structure of the chromatic fibre. Superhelical stress is revealed as plectonemic DNA that is rapidly targeted by Top2 activity.
