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Role of peroxynitrite induced structural changes on H2B histone by physicochemical method
M Asad Khan1, Khursheed Alam2, Kiran Dixit2
1Department of Biosciences, Jamia Millia Islamia, New Delhi, India.
International Journal of Biological Macromolecules
|November 5, 2015
Summary
Histone H2B is sensitive to peroxynitrite, an oxidant and nitrating agent. This study shows peroxynitrite damages H2B, altering its structure to protect DNA from oxidative and nitrosative stress.
Area of Science:
- Biochemistry
- Molecular Biology
- Cellular Stress Response
Background:
- Histones are cationic proteins crucial for DNA packaging within the nucleus.
- Histones are susceptible to damage from oxidizing and nitrating agents like peroxynitrite.
- Peroxynitrite is a biologically relevant reactive nitrogen species.
Purpose of the Study:
- To investigate the effects of peroxynitrite-induced nitration and oxidation on histone H2B.
- To characterize the structural and physicochemical changes in H2B upon exposure to peroxynitrite.
Main Methods:
- Physicochemical techniques were employed to assess modified H2B.
- High-Performance Liquid Chromatography (HPLC) was used to detect 3-nitrotyrosine.
- Polyacrylamide gel electrophoresis (PAGE) was used to observe cross-linking.
- Fourier Transform Infrared Spectroscopy (FT-IR) and fluorescence spectroscopy were utilized.
Main Results:
- Peroxynitrite significantly increased carbonyl content and dityrosine formation in H2B.
- HPLC confirmed the presence of 3-nitrotyrosine in modified H2B.
- PAGE revealed cross-linking of H2B.
- Structural analysis showed hyperchromicity, decreased tyrosine fluorescence, increased ANS-binding fluorescence, loss of β-sheet structure, and altered α-helix content, leading to a partially folded state.
Conclusions:
- Histone H2B is highly sensitive to peroxynitrite-mediated damage.
- Nitrosative and oxidative stress induce significant structural changes in H2B.
- These structural alterations may serve as a protective mechanism for DNA against peroxynitrite insult.
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