Irreversible Changes Occur in Chromatin Structure Upon Dissociation Of Histone H1
| Autor: | Marie-Françoise Hacques, Christian Marion |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Protein Denaturation
Circular dichroism Hot Temperature Protein Conformation Binding Competitive Dissociation (chemistry) Histones chemistry.chemical_compound Protein structure Histone H1 Structural Biology Micrococcal Nuclease Molecular Biology Birefringence biology Chemistry Circular Dichroism DNA General Medicine Chromatin Kinetics Crystallography Histone Spectrophotometry biology.protein Nucleic Acid Conformation Electrophoresis Polyacrylamide Gel Dialysis Micrococcal nuclease |
| Zdroj: | Journal of Biomolecular Structure and Dynamics. 8:439-458 |
| ISSN: | 1538-0254 0739-1102 |
| DOI: | 10.1080/07391102.1990.10507815 |
| Popis: | The role of histone H1 in the actual interactions bringing about chromatin folding is investigated by studying the reversibility of its dissociation. H1 was dissociated by increase of the NaCl concentration and reassociated by dialysis, without removal from the dialysis bag. To scrutinize the fidelity of this stoichiometric form of chromatin reconstitution, we use circular dichroism, nuclease digestion, thermal denaturation and the sensitive electric birefringence method. No alteration of the repeat length and no nucleosomal sliding are observed upon the reassociation procedure. However, under all the different conditions investigated, the original value of the positive electric birefringence is never recovered, indicating an irreversible change of structure. CD and melting profiles confirm that DNA-protein interactions are modified, and orientational relaxation time measurements indicate that these structural perturbations affect the salt-induced transition of polynucleosomal fibers. The striking conclusion of these studies is that variations of ionic concentration are sufficient to induce irreversible structural alterations affecting the higher-order folding of chromatin. It is of interest that the only sample which exhibits behavior upon reassociation comparable to that of native chromatin is the one which experienced the fastest salt transitions. We suggest that these conformational changes arise from the unbinding to DNA of certain basic tails of histone(s), and that a competition for DNA binding locations exists upon the reassociation. These results are then additional arguments (Mazen, A., Hacques, M.F. and Marion, C.,J. Mol. Biol. 194, 741-745 (1987)), to suggest that dissociation of H1 might modify a direct interaction between basic tails of core histones and H1. |
| Databáze: | OpenAIRE |
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