LIFE SCIENCE

Detailed explanation-1: -The linker histone H1 binds to the entry/exit sites of DNA on the surface of the nucleosomal core particle and completes the nucleosome. It influences the nucleosomal repeat length (NRL) 2 and is required to stabilize higher-order chromatin structures such as the so-called 30-nm fibre 3.

Detailed explanation-2: -Linker histone is mainly a nucleus protein that binds to the linker DNA as well as the nucleosome to enhance the condensation of the chromatin. It exerts its influence on the transcriptional activities of certain genes.

Detailed explanation-3: -Unlike the other histones, H1 does not make up the nucleosome “bead". Instead, it sits on top of the structure, keeping in place the DNA that has wrapped around the nucleosome. H1 is present in half the amount of the other four histones, which contribute two molecules to each nucleosome bead.

Detailed explanation-4: -Histones H2A, H2B, H3, and H4 are known as the core histones, and histones H1 and H5 are known as the linker histones.

Detailed explanation-5: -H1 binding depends on linker DNA trajectory. These observations suggested that linker DNA trajectory determines whether H1 can bind to nucleosomes within an array. We therefore analyzed the linker DNA trajectory at the entry and exit sites of the stacked nucleosomes in all structures.