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Title: Protein-dependent conformational behavior of DNA in chromatin

Abstract

Information from circular dichroism (CD) and DNA thermal denaturation has been used in concert to study the conformation behavior of DNA in the extended 11-nm fiber of chromatin isolated from HeLa nuclei. The histone-dependent conformational states of the system were investigated by selectively removing the hydrophilic histone domains with trypsin. These were compared to acetylated chromatin from the same source. The integrated intensity of the positive CD band for DNA above 260 nm is found to increase with the content of relatively unstressed B-form DNA. This same increase is observed along the series of whole, H1-stripped, and trypsinized chromatin samples as protein is removed. Hence, the ratio of percent hyperchromicity to integrated CD band intensity of the respective melting transitions provides useful information on the conformational state of DNA in the three principal regions of the chromatin fiber: the central loop and flanking nucleosomal regions and the linker. Results from this study suggest that central loop DNA in both hyperacetylated and control chromatin relaxes as protein is removed. However, hyperacetylated chromatin shows significantly less dependence than control chromatin upon core histone hydrophilic domains in the flanking and linker regions. Thus, histone hyperacetylation evidently relaxes DNA in chromatin with no majormore » overall conformational changes. A possible role of histone hyperacetylation may therefore be to reduce cooperativity in the unfolding transition in chromatin and thus provide for greater localized control of unfolding during transcription.« less

Authors:
;
Publication Date:
Research Org.:
Univ. of Nevada, Reno
OSTI Identifier:
5879505
Resource Type:
Journal Article
Journal Name:
Biochemistry; (United States)
Additional Journal Information:
Journal Volume: 26:10
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; CHROMATIN; MAGNETIC CIRCULAR DICHROISM; TEMPERATURE EFFECTS; DNA; CONFORMATIONAL CHANGES; ACETYLATION; ELECTROPHORESIS; HELA CELLS; MELTING POINTS; NUCLEIC ACID DENATURATION; TRANSCRIPTION; ACYLATION; CHEMICAL REACTIONS; DICHROISM; NUCLEIC ACIDS; ORGANIC COMPOUNDS; PHYSICAL PROPERTIES; THERMODYNAMIC PROPERTIES; TRANSITION TEMPERATURE; 550200* - Biochemistry

Citation Formats

Riehm, M R, and Harrington, R E. Protein-dependent conformational behavior of DNA in chromatin. United States: N. p., 1987. Web. doi:10.1021/bi00384a032.
Riehm, M R, & Harrington, R E. Protein-dependent conformational behavior of DNA in chromatin. United States. https://doi.org/10.1021/bi00384a032
Riehm, M R, and Harrington, R E. 1987. "Protein-dependent conformational behavior of DNA in chromatin". United States. https://doi.org/10.1021/bi00384a032.
@article{osti_5879505,
title = {Protein-dependent conformational behavior of DNA in chromatin},
author = {Riehm, M R and Harrington, R E},
abstractNote = {Information from circular dichroism (CD) and DNA thermal denaturation has been used in concert to study the conformation behavior of DNA in the extended 11-nm fiber of chromatin isolated from HeLa nuclei. The histone-dependent conformational states of the system were investigated by selectively removing the hydrophilic histone domains with trypsin. These were compared to acetylated chromatin from the same source. The integrated intensity of the positive CD band for DNA above 260 nm is found to increase with the content of relatively unstressed B-form DNA. This same increase is observed along the series of whole, H1-stripped, and trypsinized chromatin samples as protein is removed. Hence, the ratio of percent hyperchromicity to integrated CD band intensity of the respective melting transitions provides useful information on the conformational state of DNA in the three principal regions of the chromatin fiber: the central loop and flanking nucleosomal regions and the linker. Results from this study suggest that central loop DNA in both hyperacetylated and control chromatin relaxes as protein is removed. However, hyperacetylated chromatin shows significantly less dependence than control chromatin upon core histone hydrophilic domains in the flanking and linker regions. Thus, histone hyperacetylation evidently relaxes DNA in chromatin with no major overall conformational changes. A possible role of histone hyperacetylation may therefore be to reduce cooperativity in the unfolding transition in chromatin and thus provide for greater localized control of unfolding during transcription.},
doi = {10.1021/bi00384a032},
url = {https://www.osti.gov/biblio/5879505}, journal = {Biochemistry; (United States)},
number = ,
volume = 26:10,
place = {United States},
year = {Tue May 19 00:00:00 EDT 1987},
month = {Tue May 19 00:00:00 EDT 1987}
}