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Evolutionary conservation of histone macroH2A subtypes and domains
1University of Pennsylvania, Department of Animal Biology, School of Veterinary Medicine, Philadelphia, PA 19104-6048, USA. pehrson@vet.upenn.edu
Nucleic Acids Research
|June 5, 1998
Summary
Histone macroH2A, an unusual histone with a unique structure, shows remarkable conservation across species separated by 300 million years. Its non-histone domain may originate from ancient genes predating eukaryotes.
Area of Science:
- Molecular Biology
- Evolutionary Biology
- Genetics
Background:
- Histone macroH2A is a distinctive core histone characterized by a large non-histone region appended to a canonical H2A-like domain.
- Understanding the evolutionary conservation of this unique histone structure provides insights into eukaryotic chromatin regulation.
Purpose of the Study:
- To investigate the evolutionary conservation of the macroH2A histone's unique structural arrangement.
- To determine the evolutionary origins of the non-histone domain of macroH2A.
Main Methods:
- Cloning of chicken macroH2A cDNAs.
- Comparison of chicken macroH2A sequences with their rat counterparts.
- Bioinformatic analysis comparing the non-histone domain sequence to bacterial and viral proteins.
Main Results:
- Amino acid sequences of macroH2A subtypes are >95% identical between chicken and rat, despite ~300 million years of evolutionary divergence.
- The H2A-like region of macroH2A is completely conserved, exhibiting higher conservation than conventional H2A.
- Sequence comparisons suggest the non-histone domain originated from a gene predating eukaryotes, retaining its ancestral function.
Conclusions:
- The macroH2A histone's unique structure is highly conserved throughout vertebrate evolution.
- The non-histone domain of macroH2A has ancient evolutionary origins, likely stemming from a prokaryotic or viral gene.
- This conservation suggests a critical, retained function for the non-histone domain in eukaryotic cells.