The oxidised histone octamer does not form a H3 disulphide bond
Christopher M Wood1, Sirirath Sodngam, James M Nicholson
1School of Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK. c.m.wood@ljmu.ac.uk
Biochimica Et Biophysica Acta
|August 22, 2006
Summary
Histone octamers form a stable H3-H3' dimer interface in oxidized crystals, explaining the dimer band observed in SDS-PAGE gels. This stability arises from specific structural changes within the histone octamer.
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biophysics
Background:
- Native histone octamers exhibit an H3 dimer band on SDS-PAGE gels under specific conditions.
- Histone octamers are fundamental nucleoprotein complexes involved in DNA packaging.
Purpose of the Study:
- To investigate the structural basis for the observed H3 dimer band in histone octamers.
- To elucidate the role of oxidation and disulfide bond formation in histone octamer stability.
Main Methods:
- Crystallization of native histone octamers from chicken erythrocytes using S-nitrosoglutathione as an oxidizing agent.
- X-ray diffraction data acquisition and structure determination to 2.10 Å resolution.
- Free-energy calculations and analysis of hydrogen bonding networks.
Main Results:
- The oxidized histone octamer crystal structure revealed a stable H3-H3' dimer interface, with a reduced c-axis length.
- Inter-sulfur distance between H3 cysteines decreased to 6 Å in the oxidized form.
- Disulfide bond formation in the H3-H3' interface was found to be incompatible with stable tetramer formation.
Conclusions:
- The stable H3-H3' dimer interface in oxidized histone octamers explains the observed dimer band on SDS-PAGE.
- Oxidation and subsequent structural rearrangements contribute to the thermodynamic stability of the H3-H3' interface.
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