Mangenot Stéphanie, Keller Simon, Rädler Joachim
Ludwig-Maximilians-Universität, Sektion Physik, Geschwister-Scholl-Platz 1, D-80539 Munich, Germany.
Biophys J. 2003 Sep;85(3):1817-25. doi: 10.1016/S0006-3495(03)74610-4.
We studied the diffusion of native and trypsinized nucleosome core particles (NCPs), in aqueous solution and in concentrated DNA solutions (0.25-100 mg/ml) using fluorescence correlation spectroscopy (FCS). The highest DNA concentrations studied mimic the DNA density inside the cell nucleus. The diffusion coefficient of freely diffusing NCPs depends on the presence or absence of histone tails and is affected by the salt concentration due to the relaxation effect of counterions. NCPs placed in a network of long DNA molecules (30-50 kbp) reveal anomalous diffusion. We demonstrate that NCPs diffusion is in agreement with known particle transport in entangled macromolecular solutions as long as the histone tails are folded onto the particles. In contrast, when these tails are unfolded, the reversible adsorption of NCPs onto the DNA network has to be taken into account. This is confirmed by the fact that removal of the tails leads to reduction of the interaction between NCPs and the DNA network. The findings suggest that histone tail bridging plays an important role in chromatin dynamics.
我们使用荧光相关光谱法（FCS）研究了天然和经胰蛋白酶处理的核小体核心颗粒（NCPs）在水溶液和浓DNA溶液（0.25 - 100 mg/ml）中的扩散情况。所研究的最高DNA浓度模拟了细胞核内的DNA密度。自由扩散的NCPs的扩散系数取决于组蛋白尾巴的有无，并由于抗衡离子的松弛效应而受盐浓度影响。置于长DNA分子（30 - 50 kbp）网络中的NCPs表现出反常扩散。我们证明，只要组蛋白尾巴折叠在颗粒上，NCPs的扩散就与已知的缠结大分子溶液中的颗粒运输一致。相反，当这些尾巴展开时，必须考虑NCPs在DNA网络上的可逆吸附。去除尾巴会导致NCPs与DNA网络之间的相互作用减弱，这一事实证实了这一点。这些发现表明组蛋白尾巴桥接在染色质动力学中起重要作用。
