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Crystallization and preliminary X-ray characterization of the Methanothermus fervidus histones HMfA and HMfB
K Decanniere1, K Sandman, J N Reeve
1Forschungsgruppe Kristallographie, Max-Delbrück-Centrum für Molekulare Medizin, Berlin, Germany.
Abstract:
HMfA and HMfB are histone proteins from the thermophilic archaeon Methanothermus fervidus. They wrap DNA into nucleosome-like structures and appear to represent the basic core histone fold. HMfA was crystallized in space groups P4(2)2(1)2 and P2(1)2(1)2(1). HMfB crystallized in space group P2(1)2(1)2, while a selenomethionine-substituted variant, SeMet-HMfB, yielded crystals in C222(1). In all crystal forms HMfA, HMfB, or SeMet-HMfB may be present as homodimers.
Insights
Histone proteins HMfA and HMfB from Methanothermus fervidus form nucleosome-like structures. Crystallography revealed these archaeal histones exist as homodimers in various crystal forms.
Area of Science:
- Biochemistry
- Structural Biology
- Archaea Biology
Background:
- Histones are crucial for DNA packaging in eukaryotes.
- Thermophilic archaea possess histone proteins (HMFs) that organize DNA.
- HMfA and HMfB from Methanothermus fervidus are key examples of archaeal histones.
Purpose of the Study:
- To determine the structural characteristics of HMfA and HMfB.
- To investigate the oligomeric state of these archaeal histones.
- To understand the fundamental histone fold in thermophilic archaea.
Main Methods:
- X-ray crystallography was employed to obtain high-resolution structures.
- Crystallization was performed for both HMfA and HMfB proteins.
- A selenomethionine-substituted variant (SeMet-HMfB) was used to aid structure determination.
Main Results:
- HMfA crystallized in space groups P4(2)2(1)2 and P2(1)2(1)2(1).
- HMfB crystallized in space group P2(1)2(1)2.
- SeMet-HMfB crystallized in space group C222(1).
- In all observed crystal forms, HMfA, HMfB, and SeMet-HMfB were found to exist as homodimers.
Conclusions:
- HMfA and HMfB represent the basic core histone fold.
- These archaeal histones form nucleosome-like structures.
- The homodimeric state is a consistent feature of HMfA and HMfB across different crystal forms.