Nucleosome structure
From Proteopedia
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Nucleosomes are the basic building blocks of chromatin fibers. A nucleosome consists of a core containing an octamer of histone proteins and a DNA molecule 146 bp long wound around this core in two complete turns. The includes four types of proteins: , , and . Histone proteins are organized in dimers so:
- Two H3-H4 dimers
- Two H2A-H2B dimers
- molecule wound in around octamer. Some complete the whole structure.
The main secondary structure in is .
If we highlight the different types of amino acid residues on the we can see that and are arranged so positively charged residues are in , where they can form ionic interactions (salt bridges) with . This distribution of electric charges stabilizes the whole structure.
See Also
References
This page is based on 1aoi file from Proteopedia.
1aoi is a 10 chain structure with sequence from Xenopus laevis. The July 2000 RCSB PDB Molecule of the Month feature on Nucleosome by David S. Goodsell is 10.2210/rcsb_pdb/mom_2000_7. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
