Nucleosome structure
From Proteopedia
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*<scene name='60/602771/Nucleosoma/3'>DNA</scene> molecule wound in <scene name='60/602771/Nucleosoma/4'>two complete turns</scene> around octamer. Some <scene name='60/602771/Nucleosoma/5'>manganese ions</scene> complete the whole structure. | *<scene name='60/602771/Nucleosoma/3'>DNA</scene> molecule wound in <scene name='60/602771/Nucleosoma/4'>two complete turns</scene> around octamer. Some <scene name='60/602771/Nucleosoma/5'>manganese ions</scene> complete the whole structure. | ||
| - | The | + | The main secondary structure in <scene name='60/602771/Octamero/2'>histones</scene> is <scene name='60/602771/Secondarystructure/1'>alpha helices</scene>. |
If we situate the different types of amino acid residues in <scene name='60/602771/Esqueleto/1'>protein skeleton</scene> we can see that <scene name='60/602771/Residuosnegativos/1'>negatively charged residues</scene> and <scene name='60/602771/Residuospositivos/1'>positively charged residues</scene> are arranged so positively charged residues are in <scene name='60/602771/Periferia/1'>peripherycal positions</scene>, where they can stablish ionic interations with <scene name='60/602771/Interacciones/1'>phosphate groups on DNA molecule</scene>. Such electric charges distributions stabilizes the whole structure. | If we situate the different types of amino acid residues in <scene name='60/602771/Esqueleto/1'>protein skeleton</scene> we can see that <scene name='60/602771/Residuosnegativos/1'>negatively charged residues</scene> and <scene name='60/602771/Residuospositivos/1'>positively charged residues</scene> are arranged so positively charged residues are in <scene name='60/602771/Periferia/1'>peripherycal positions</scene>, where they can stablish ionic interations with <scene name='60/602771/Interacciones/1'>phosphate groups on DNA molecule</scene>. Such electric charges distributions stabilizes the whole structure. | ||
Revision as of 17:14, 10 February 2016
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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 histone protein octamer includes four types of proteins: , , y . 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 situate the different types of amino acid residues in we can see that and are arranged so positively charged residues are in , where they can stablish ionic interations with . Such electric charges distributions stabilizes the whole structure.
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.
