Structure, Diffusion, and Relaxation in a Charge-Neutral ProTalpha-Histone H1 Condensate
Abstract
Condensates formed by oppositely charged intrinsically disordered proteins provide model systems for understanding how transient electrostatic interactions govern structure and dynamics in biomolecular assemblies. Here we investigate a nearly charge-neutral condensate composed of 50 Prothymosin alpha (ProTalpha) and 40 Histone H1 molecules using a single-bead-per-residue coarse-grained model combining the HPS hydropathy model for disordered regions with a Go model for the globular domain of Histone H1 under NPT conditions at pressures from 2 to 12 bar. We find that chain dimensions, including the radius of gyration (Rg), end-to-end distance (Ree), and their ratio R, are insensitive to pressure, indicating that chain conformations remain largely unchanged over the pressure range studied. Histone H1 exhibits systematically larger values of R than ProTalpha because of its globular-core plus disordered-tail architecture. Translational diffusion coefficients decrease monotonically with pressure, from approximately 0.22 to 0.06 nm^2/ns, with substantial chain-to-chain heterogeneity comparable to the mean diffusion coefficient. Chain relaxation follows a stretched exponential with beta less than 1 that decreases with pressure. ProTalpha relaxation times of approximately 12 to 40 ns obey Rouse scaling, whereas Histone H1 deviates because of the internal constraint imposed by its globular domain. ProTalpha-Histone H1 contact lifetimes of approximately 0.43 to 0.56 ns are much shorter than the Rouse relaxation time, placing the system firmly in the fast-exchange regime where transient electrostatic contacts renormalize chain friction rather than acting as permanent cross-links, consistent with the moderate stretching exponent beta of approximately 0.55 to 0.70 observed across all pressures.
Related
- Diffusion stabilises time-periodic solutions in conservation laws coupled to a relaxation oscillator
- Universal link between structural relaxation and self-diffusion in simple supercooled liquids
- Through-thickness coupling of diffusion and viscoelastic relaxation in the transient bending of bilayer microcantilevers
- Scaling law for the diffusion coefficient in vibration-driven crater relaxation
- Spin relaxation of heavy quarks from momentum diffusion in the quark-gluon plasma
BibTeX
@misc{bhattacharya2026structure,
title = {{Structure, Diffusion, and Relaxation in a Charge-Neutral ProTalpha-Histone H1 Condensate}},
author = {Aniket Bhattacharya},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2607.29639},
eprint = {2607.29639},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.29639},
}
RIS
TY - UNPB
TI - Structure, Diffusion, and Relaxation in a Charge-Neutral ProTalpha-Histone H1 Condensate
AU - Aniket Bhattacharya
PY - 2026
DA - 2026/10/28
PB - arXiv
DO - 10.48550/arxiv.2607.29639
UR - https://arxiv.org/abs/2607.29639
AB - Condensates formed by oppositely charged intrinsically disordered proteins provide model systems for understanding how transient electrostatic interactions govern structure and dynamics in biomolecular assemblies. Here we investigate a nearly charge-neutral condensate composed of 50 Prothymosin alpha (ProTalpha) and 40 Histone H1 molecules using a single-bead-per-residue coarse-grained model combining the HPS hydropathy model for disordered regions with a Go model for the globular domain of Histone H1 under NPT conditions at pressures from 2 to 12 bar. We find that chain dimensions, including the radius of gyration (Rg), end-to-end distance (Ree), and their ratio R, are insensitive to pressure, indicating that chain conformations remain largely unchanged over the pressure range studied. Histone H1 exhibits systematically larger values of R than ProTalpha because of its globular-core plus disordered-tail architecture. Translational diffusion coefficients decrease monotonically with pressure, from approximately 0.22 to 0.06 nm^2/ns, with substantial chain-to-chain heterogeneity comparable to the mean diffusion coefficient. Chain relaxation follows a stretched exponential with beta less than 1 that decreases with pressure. ProTalpha relaxation times of approximately 12 to 40 ns obey Rouse scaling, whereas Histone H1 deviates because of the internal constraint imposed by its globular domain. ProTalpha-Histone H1 contact lifetimes of approximately 0.43 to 0.56 ns are much shorter than the Rouse relaxation time, placing the system firmly in the fast-exchange regime where transient electrostatic contacts renormalize chain friction rather than acting as permanent cross-links, consistent with the moderate stretching exponent beta of approximately 0.55 to 0.70 observed across all pressures.
ER -