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Studies on the mechanism of nucleosome remodeling by RSC and SWI/SNF

Abstract : In eukaryotic cell the DNA is organized in the nucleus in the form of chromatin, the fundamental unit of which is called as the nucleosome. Organization of DNA into the nucleosomes presents a strong barrier for various processes which require access to the DNA like transcription, replication and repair. To overcome this problem cells utilize a variety of methods, ATP dependent chromatin remodeling being one of the most important of them. A common feature of all the remodelers is that they are able to reposition the nucleosomes along the DNA at the expense of ATP.

In the present work, we have studied the mechanism of nucleosome mobilization by RSC and SWI/SNF, two well characterized remodelers from yeast. A combinatorial approach was employed using high resolution microscopy namely Electron cryo-Microscopy (EC-M) and Atomic Force Microscopy (AFM) together with novel biochemical approaches. We have shown that the nucleosome mobilization by RSC and SWI/SNF involves hitherto unknown intermediate structures. These remodeled nucleosome particles ‘The Remosomes' possess characteristic structural features. Our AFM studies show that ~180 bp of DNA is associated with the histone octamer as compared to ~147 bp in the canonical nucleosomes. Using DNaseI footprinting and EC-M we have shown that the path of DNA around the histone octamer is highly perturbed. Moreover, these particles represent an ensemble many different structures rather than one defined specie. The novel ‘in gel one pot assay' showed that accessibility profile of these particles is completely different from that of canonical nucleosomes and they are accessible all along the path of DNA.

We have also addressed the question of inhibition of nucleosome mobilization due to incorporation of histone variant H2A.Bbd in the nucleosomes. We show that the docking domain of histone H2A is essential for SWI/SNF and RSC induced nucleosome sliding. Furthermore, we demonstrate that the reason for inability of these nucleosomes to slide is due to a faulty generation of ‘Remosome' intermediates.
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Contributor : Manu Shubhdarshan Shukla <>
Submitted on : Monday, September 7, 2009 - 12:42:20 PM
Last modification on : Friday, November 6, 2020 - 4:14:35 AM
Long-term archiving on: : Tuesday, June 15, 2010 - 11:17:17 PM


  • HAL Id : tel-00413908, version 1


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Manu Shubhdarshan Shukla. Studies on the mechanism of nucleosome remodeling by RSC and SWI/SNF. Biomolecules [q-bio.BM]. Université Joseph-Fourier - Grenoble I, 2009. English. ⟨tel-00413908⟩



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