Emergence of compact-disordered phase in a polymer Potts model

TL;DR

This paper introduces a polymer Potts model to study chromatin structure, revealing a new compact-disordered phase where the polymer is compact but epigenetic patterns are disordered, influenced by interaction energy and modification fraction.

Contribution

It presents a novel polymer Potts model with an interaction energy offset, combining mean-field analysis and molecular dynamics to explore chromatin phase behavior.

Findings

Identification of a compact-disordered phase in the model

Dependence of phase emergence on interaction energy offset

Correlation between nucleosome modification fraction and phase

Abstract

One of the central problems in epigenetics is how epigenetic modification patterns and chromatin structure are regulated in the cell nucleus. The polymer Potts model, a recently studied model of chromatins, is introduced with an offset in the interaction energy as a parameter, and the equilibrium properties are investigated using the mean-field analysis of the lattice model and molecular dynamics simulations of the off-lattice model. The results show that in common with both models, a phase emerges, which could be called the compact-disordered phase, in which the polymer conformation is compact and the epigenetic modification pattern is disordered, depending on the offset in the interaction energy and the fraction of the modified nucleosomes.