TOD

Abstract

Human DNA is two meters long and is folded into a structure that fits in a cell nucleus of just 5 microns in diameter. Recently developed Hi-C technique provides comprehensive information about genome folding. Our analysis of Hi-C data provides and biophysical polymer modeling show that scaling observed in the data is consistent with non-equilibrium and unknotted polymer state – the crumpled (fractal) globule. We demonstrate that the fractal globule emerges as a result of polymer collapse and has a short lifetime, rapidly mixing while remaining largely unknotted. Long-time dynamics of a condensed polymer reveals that spatial and topological equilibration happen at vastly different time scales and that topological constrains have little effect on relatively short and flexible chains.