# Histone H3 tail charge patterns govern nucleosome condensate formation and dynamics

## TL;DR

This paper shows how changes in the H3 histone tail affect how nucleosomes form and behave in chromatin condensates.

## Contribution

The study reveals how specific charge patterns in the H3 tail regulate nucleosome phase separation and condensate dynamics.

## Key findings

- Terminal and central regions of the H3 tail differentially modulate nucleosome condensate phase boundaries and viscosity.
- H3 tail mobility within condensates correlates with condensate viscosity as shown by NMR relaxation experiments.
- Basic residue arrangement in the H3 tail critically regulates nucleosome phase separation and chromatin microenvironment.

## Abstract

Emerging models of nuclear organization suggest that chromatin forms functionally distinct microenvironments through phase separation. As chromatin architecture is organized at the level of the nucleosome and regulated by histone post-translational modifications, we investigated how these known regulatory mechanisms influence nucleosome phase behavior. By systematically altering charge distribution within the H3 tail, we found that the terminal and central regions modulate the phase boundary and tune nucleosome condensate viscosity differentially, as revealed by microscopy-based assays, microrheology, and simulations. Nuclear magnetic resonance relaxation experiments revealed that H3 tails remain dynamically mobile within condensates, and their mobility correlates with condensate viscosity. These results demonstrate that the number, identity, and spatial arrangement of basic residues in the H3 tail critically regulate nucleosome phase separation. Our findings support a model in which nucleosomes, through their intrinsic properties and modifications, actively shape the local chromatin microenvironment—providing new insight into the histone language in chromatin condensates.

Graphical Abstract