TY - JOUR

T1 - Structure, dynamics, and stability of the globular domain of human linker histone H1.0 and the role of positive charges

AU - Martinsen, Jacob H.

AU - Saar, Daniel

AU - Fernandes, Catarina B.

AU - Schuler, Benjamin

AU - Bugge, Katrine

AU - Kragelund, Birthe B.

PY - 2022

Y1 - 2022

N2 - Linker histone H1 (H1) is an abundant chromatin-binding protein that acts as an epigenetic regulator binding to nucleosomes and altering chromatin structures and dynamics. Nonetheless, the mechanistic details of its function remain poorly understood. Recent work suggest that the number and position of charged side chains on the globular domain (GD) of H1 influence chromatin structure and hence gene repression. Here, we solved the solution structure of the unbound GD of human H1.0, revealing that the structure is almost completely unperturbed by complex formation, except for a loop connecting two antiparallel beta-strands. We further quantified the role of the many positive charges of the GD for its structure and conformational stability through the analysis of 11 charge variants. We find that modulating the number of charges has little effect on the structure, but the stability is affected, resulting in a difference in melting temperature of 26 K between GD of net charge +5 versus +13. This result suggests that the large number of positive charges on H1-GDs have evolved for function rather than structure and high stability. The stabilization of the GD upon binding to DNA can thus be expected to have a pronounced electrostatic component, a contribution that is amenable to modulation by posttranslational modifications, especially acetylation and phosphorylation.

AB - Linker histone H1 (H1) is an abundant chromatin-binding protein that acts as an epigenetic regulator binding to nucleosomes and altering chromatin structures and dynamics. Nonetheless, the mechanistic details of its function remain poorly understood. Recent work suggest that the number and position of charged side chains on the globular domain (GD) of H1 influence chromatin structure and hence gene repression. Here, we solved the solution structure of the unbound GD of human H1.0, revealing that the structure is almost completely unperturbed by complex formation, except for a loop connecting two antiparallel beta-strands. We further quantified the role of the many positive charges of the GD for its structure and conformational stability through the analysis of 11 charge variants. We find that modulating the number of charges has little effect on the structure, but the stability is affected, resulting in a difference in melting temperature of 26 K between GD of net charge +5 versus +13. This result suggests that the large number of positive charges on H1-GDs have evolved for function rather than structure and high stability. The stabilization of the GD upon binding to DNA can thus be expected to have a pronounced electrostatic component, a contribution that is amenable to modulation by posttranslational modifications, especially acetylation and phosphorylation.

KW - CD

KW - histone

KW - NMR

KW - nucleosome

KW - protein electrostatics

KW - protein stability

KW - protein structure

KW - CRYSTAL-STRUCTURE

KW - GENE-EXPRESSION

KW - CHROMATIN

KW - BINDING

KW - RECOGNITION

U2 - 10.1002/pro.4281

DO - 10.1002/pro.4281

M3 - Journal article

C2 - 35066947

VL - 31

SP - 918

EP - 932

JO - Protein Science

JF - Protein Science

SN - 0961-8368

IS - 4

ER -