2016Zhang DNANG

Citation

3D Structural Dynamics and Fluctuations of DNA-Nanogold Conjugates by Individual-Particle Electron Tomography, Lei Zhang, Dongsheng Lei, Jessica M. Smith, Huimin Tong, Xing Zhang, Zhuoyang Lu, Paul Alivisatos and Gang Ren, Nature Communications, (2016), 7:11083. doi: 10.1038

Abstract

It has been proposed that the intrinsic property of nucleosome arrays to undergo liquid-liquid phase separation (LLPS) in vitro is responsible for chromatin domain organization in vivo. However, understanding nucleosomal LLPS has been hindered by the challenge to characterize the structure of the resulting heterogeneous condensates. We used cryo-electron tomography and deep-learning-based 3D reconstruction/segmentation to determine the molecular organization of condensates at various stages of LLPS. We show that nucleosomal LLPS involves a two-step process: a spinodal decomposition process yielding irregular condensates, followed by their unfavorable conversion into more compact, spherical nuclei that grow into larger spherical aggregates through accretion of spinodal materials or by fusion with other spherical condensates. Histone H1 catalyzes more than 10-fold the spinodal-to-spherical conversion. We propose that this transition involves exposure of nucleosome hydrophobic surfaces causing modified inter-nucleosome interactions. These results suggest a physical mechanism by which chromatin may transition from interphase to metaphase structures.

Keywords

Single molecule structure, individual-particle electron tomography, IPET, DNA nanogold conjugate

Paper links

https://www.nature.com/articles/ncomms11083

Related video

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