H2A and H2B tails are essential to properly reconstitute nucleosome core particles |
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Authors: | Aurélie Bertin Dominique Durand Madalena Renouard Françoise Livolant Stéphanie Mangenot |
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Institution: | (1) Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris-Sud, 91405 Orsay Cedex, France;(2) IBBMC, CNRS UMR 8619, Université Paris-Sud, 91405 Orsay Cedex, France;(3) Present address: Nogales Laboratory, Molecular and Cellular Biology Department, University of California, Berkeley, CA 94720-3200, USA |
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Abstract: | The conformation of recombinant Nucleosome Core Particles (NCPs) lacking H2A and H2B histone tails (gH2AgH2B) are studied.
The migration of these particles in acrylamide native gels is slowed down compared to intact reconstituted NCPs. gH2AgH2B
NCPs are also much more sensitive to nuclease digestion than intact NCPs. Small angle X-ray scattering (SAXS) experiments
point out that the absence of H2A and H2B tails produces small but significant conformational changes of the octamers conformation
(without wrapped DNA), whereas gH2AgH2B NCP conformations are significantly altered. A separation of about 25–30 bp from the
core could account for the experimental curves, but other types of DNA superhelix deformation cannot be excluded. The distorted
gH2AgH2B octamer may not allow the correct winding of DNA around the core. The absence of the H2A and H2B tails would further
prevent the secondary sliding of the DNA around the core and therefore impedes the stabilisation of the particle. Cryo-electron
microscopy on the same particles also shows a detachment of DNA portions from the particle core. The effect is even stronger
because the vitrification of the samples worsens the instability of gH2AgH2B NCPs. |
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Keywords: | Nucleosome Histone tails SAXS Chromatin |
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