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Histone stoichiometry and DNA circularization in archaeal nucleosomes
K A Bailey1, C S Chow, J N Reeve
1Department of Microbiology, Ohio State University, Columbus, OH 43210, USA and Department of Chemistry,Wayne State University, Detroit, MI 48202, USA.
Nucleic Acids Research
|December 24, 1998
Summary
Archaeal histone B (rHMfB) forms stable nucleosomes with DNA longer than 52 bp. These archaeal nucleosomes resemble eukaryotic histone complexes, suggesting a conserved DNA-packaging mechanism.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Archaeal histones are structural homologs of eukaryotic histones.
- Understanding archaeal DNA organization provides insights into the evolution of the nucleus.
Purpose of the Study:
- To investigate the DNA binding and nucleosome formation capabilities of recombinant archaeal histone B (rHMfB) from Methanothermus fervidus.
- To characterize the structure and stability of archaeal nucleosomes.
Main Methods:
- Complex formation assays with varying DNA lengths.
- Biochemical analysis using radiolabeled histone and DNA.
- DNA ligase treatment to assess DNA bending and circularization.
- Electrophoretic analysis of supercoiled DNA.
Main Results:
- rHMfB formed stable complexes with DNA molecules of 52 bp and longer, but not 39 bp.
- Archaeal nucleosomes contain an archaeal histone tetramer.
- DNA ligation experiments demonstrated DNA bending and wrapping around the histone tetramer.
- Archaeal nucleosomes assembled with supercoiled DNA were more stable than those with linear DNA.
Conclusions:
- Archaeal nucleosomes exhibit structural similarities to eukaryotic (H3+H4)2 tetramers.
- DNA length and topology influence archaeal nucleosome formation and stability.
- These findings suggest a conserved mechanism for DNA packaging across archaea and eukaryotes.