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Proceedings Paper

Picosecond laser cross: linking histones to DNA in chromatin: implication in studying histone/DNA interactions
Author(s): Dimitar A. Angelov; S. Dimitrov; E. Keskinova; I. Pashev; V. Russanova; Yu. Stefanovsky
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Paper Abstract

A picosecond UV laser radiation was used to cross-link proteins to DNA in nuclei, whole cells and different chromating preparations. All histones as well as high-mobility group 1 proten were identified immunochemically in the covalently linked protein-DNA complexes. Irradiation of the nuclieohistone resulted in cross-linking 20% of bound histones to DNA as a result of two-quantum photoreaction with a maximum quantum yield 3.10 -4 for double stranded DNA. When nuclei, total bromatin Hi-depleted chromatin and core particles were irradiated and then trypsinized or treated with clostripain to cleave respectively the N-, C- and N- terminal histone tails, no histones have been found covalently linked to DNA. However whilst the yield of cross-links was similar in total and H1-depleted chromatin in core particples the efficiencey was 3-4 times lower for H2A, H2B and H4 10-12 times lower for H3. This finding we consider as a direct evidence for interaction of non structured N- tails of core histones with linker DNA. Cross-linking in core particles depends on the ionic strength. All histones were identified in the complex formed up to 0.4 N NaCl, no cross-linking was observed when irradiation was carried out at salt concentration higher than 0.4 M. The cross-linking ability was preserved both upon physiological acetylation of histones knows to be restriced to the N-terminal tails and with chemically acetylated chromatin. This finding is direct evidence that postsynthetic histone acetylation does not release the N-terminal tails from interaction with DNA.

Paper Details

Date Published: 1 May 1991
PDF: 10 pages
Proc. SPIE 1403, Laser Applications in Life Sciences, (1 May 1991); doi: 10.1117/12.57287
Show Author Affiliations
Dimitar A. Angelov, Institute of Solid State Physics (Bulgaria)
S. Dimitrov, Institute of Molecular Biology (Bulgaria)
E. Keskinova, Institute of Solid State Physics (Bulgaria)
I. Pashev, Institute of Molecular Biology (Bulgaria)
V. Russanova, Institute of Molecular Biology (Bulgaria)
Yu. Stefanovsky, Institute of Molecular Biology (Bulgaria)


Published in SPIE Proceedings Vol. 1403:
Laser Applications in Life Sciences

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