Etudes sur le mécanisme de remodelage des nucléosomes par ...
Etudes sur le mécanisme de remodelage des nucléosomes par ...
Etudes sur le mécanisme de remodelage des nucléosomes par ...
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tel-00413908, version 1 - 7 Sep 2009<br />
II.1 Summary<br />
We have studied the mechanism of RSC nuc<strong>le</strong>osome mobilization by using high resolution<br />
microscopy and biochemical techniques. AFM analysis shows that two types of products are<br />
generated during the RSC remo<strong>de</strong>ling: (i) stab<strong>le</strong> non-mobilized <strong>par</strong>tic<strong>le</strong>s, termed remosomes,<br />
which contain 180-190 bp of DNA associated with the histone octamer and, (ii) mobilized<br />
<strong>par</strong>tic<strong>le</strong>s located at the end of DNA. E<strong>le</strong>ctron-cryo microscopy reveals that individual<br />
remosomes exhibit a distinct, variab<strong>le</strong> highly irregular DNA trajectory. The use of the novel<br />
“in gel one pot assay” for studying the accessibility of nuc<strong>le</strong>osomal DNA towards restriction<br />
enzymes all along its <strong>le</strong>ngth and DNase I footprinting <strong>de</strong>monstrate that the histone-DNA<br />
interactions within the remosomes are strongly perturbed, <strong>par</strong>ticularly in the vicinity of the<br />
nuc<strong>le</strong>osome dyad. The data suggest a two step mechanism of RSC nuc<strong>le</strong>osome remo<strong>de</strong>ling<br />
consisting of initial formation of a remosome followed by mobilization. In agreement with<br />
this mo<strong>de</strong>l, we experimentally show that the remosomes are intermediate products generated<br />
during the first step of the remo<strong>de</strong>ling reaction, which are further efficiently mobilized by<br />
RSC.<br />
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