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Histone cross-linking by transglutaminase.
Jae-Hong Kim1, Kang Hoon Nam, Oh-Seok Kwon
1Department of Biochemistry and Molecular Biology, College of Medicine, Seoul National University, 28 Yongon-Dong, Chongno-Gu, Seoul 110-799, South Korea.
Biochemical and Biophysical Research Communications
|June 11, 2002
Summary
Tissue-type transglutaminase (tTGase) cross-links core histones H2A and H2B, but only when they are not organized in nucleosomes. This histone modification may aid chromatin condensation during red blood cell differentiation.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Transglutaminases catalyze protein cross-linking via isopeptide bonds.
- Tissue-type transglutaminase (tTGase) is widespread but its natural substrates are unknown.
Purpose of the Study:
- To identify natural substrates for tTGase.
- To investigate tTGase cross-linking of core histones.
Main Methods:
- In vitro analysis of tTGase activity on core histones.
- Examination of histone cross-linking in nucleosome-organized and free states.
- Analysis of cross-linked histones in chicken erythrocytes.
Main Results:
- Core histone subunits H2A and H2B were specifically cross-linked by tTGase.
- Cross-linking occurred between specific glutamine and lysine residues on H2A and H2B, respectively.
- Cross-linking was observed only when histones were free, not within nucleosomes.
- Significant amounts of cross-linked H2A-H2B were found in chicken erythrocytes.
Conclusions:
- tTGase-mediated cross-linking represents a novel core histone modification.
- This modification may contribute to chromatin condensation during erythrocyte differentiation.