Nucleosome Chiral Transition under Positive Torsional Stress in Single Chromatin Fibers
| Autor: | Bancaud, Aurelien, Wagner, Gaudeline, Silva, Natalia Conde e, Lavelle, Christophe, Wong, Hua, Mozziconacci, Julien, Barbi, Maria, Sivolob, Andrei, Cam, Eric Le, Mouawad, Liliane, Viovy, Jean-Louis, Victor, Jean-Marc, Prunell, Ariel |
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| Rok vydání: | 2007 |
| Předmět: | |
| Zdroj: | Molecular Cell 27, 135-147, 2007 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1016/j.molcel.2007.05.037 |
| Popis: | Using magnetic tweezers to investigate the mechanical response of single chromatin fibers, we show that fibers submitted to large positive torsion transiently trap positive turns, at a rate of one turn per nucleosome. A comparison with the response of fibers of tetrasomes (the (H3-H4)2 tetramer bound with ~50 bp of DNA) obtained by depletion of H2A-H2B dimers, suggests that the trapping reflects a nucleosome chiral transition to a metastable form built on the previously documented righthanded tetrasome. In view of its low energy, <8 kT, we propose this transition is physiologically relevant and serves to break the docking of the dimers on the tetramer which in the absence of other factors exerts a strong block against elongation of transcription by the main RNA polymerase. Comment: 33 pages (double spacing), 7 figures |
| Databáze: | arXiv |
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